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Hemolymph was collected from recently fed desert locusts either by adsorption onto filter paper, or by centrifugation and methanol extraction. Whole hemolymph caused both the short-circuit current (Isc) and open-circuit transepithelial electropotential difference (PD) across locust recta mounted in Ussing-type chambers to double during the steady-state period. Methanol extracts of hemolymph caused similar but smaller increases in Isc. The transepithelial resistance (R) did not change. Simultaneous measurements of 36Cl− fluxes indicated that all of the increase in Isc following stimulation could be accounted for by a parallel increase in net Cl− absorption from the lumen side. With the exception of an initial small biphasic fluctuation in Isc, stimulation by hemolymph exhibited identical characteristics to those produced by submaximal dosages of corpora cardiaca (CC). Cardiatectomy drastically reduced the stimulatory activity of hemolymph, suggesting that this neuroendocrine organ is the source of the active factor (chloride transport stimulating hormone (CTSH)) in hemolymph.

Freshly caught intermolt lobsters show a highly significant elevation of blood glucose after a few minutes of mild stress. Females show a significantly greater increase than males. The small amounts of other sugars in the blood are great enough to explain the increase in glucose, and chromatographic analysis shows that they diminish under stress. In postmolt animals the stress hyperglycaemia is not as great but is still significant; the difference between the sexes is not apparent. Lobsters held in commercial pounds were found to be in a hyperglycaemic condition. The stress of commercial handling and prolonged fasting brings about significant changes in blood sugars and the sexes react differently. The rather better survival of females under these conditions may also be significant.

The size at which crustaceans become mature can be a useful gauge in the study of environmental effects on field populations. The use of probability paper in rigorously defining the mean size at onset of sexual maturity avoids some of the confusion inherent in other methods of assessing size at maturity and permits an objective comparison of differences between discrete populations. Both logical and mathematical considerations in the use of probability paper for analyzing field data have been treated; and some sample data reveal how one might detect environmental effects on population structure. In this case the data indicated that mole crabs (Emerita analoga) may have grown at different rates in proximate populations.

This paper provides the first description of the cellular composition of the gill epithelium of feeding adults of Ichthyomyzon unicuspis Hubbs and Trautman, 1937 (silver lamprey), a parasitic species of lamprey that is confined to fresh water. The surface layer of this epithelium consists solely of pavement cells and intercalated mitochondria-rich cells, which are the only cell types found in all freshwater stages of lampreys and thus considered responsible for the uptake of Na+ and Cl– in hypotonic environments. This epithelium does not contain, however, the chloride cells present during the marine parasitic phase of anadromous lamprey species, such as Petromyzon marinus L., 1758 (sea lamprey), and which are responsible for secreting excess Na+ and Cl–. The absence of this cell type in parasitic adults of I. unicuspis also differs from its presence in parasitic adults of landlocked P. marinus and metamorphosing individuals of the exclusively freshwater nonparasitic species Lethenteron appendix (DeKay, 1842) (American brook lamprey), and which thus reflects the retention of a cell type that was crucial for osmoregulation during the marine phase of their respective anadromous parasitic ancestors. The absence of chloride cells in I. unicuspis is consistent with the hypothesis that Ichthyomyzon, which is at or close to the base of the phylogenetic tree for Northern Hemisphere lampreys (Petromyzontidae), evolved in fresh water or has been confined to fresh water for a very long period.

Male alternative reproductive tactics have been described in many mating systems. In fishes, these tactics typically involve a territorial male that defends a spawning site or nest and a parasitic male that uses sneaking or female mimicry to steal fertilizations from the territorial male. In this paper, we use molecular genetic markers to examine the success of males that adopt alternative reproductive tactics in two sunfishes, comprising the bluegill ( Lepomis macrochirus Rafinesque, 1819) and the pumpkinseed ( Lepomis gibbosus (L., 1758)). In sunfishes, the tactics are referred to as parental (territorial male) and cuckolder (parasitic male). We show that cuckoldry rates peak in the second trimester of the breeding season in bluegill, whereas cuckoldry rates are lowest during this period in pumpkinseed. We also show that paternity of parental male bluegill is positively correlated with body condition, but not body length or mass. No relationship between these phenotypic variables and paternity in pumpkinseed was found. We discuss the patterns of cuckoldry in relation to differences between the species in mating opportunities, parental male defence ability, and cuckolder density. Finally, we discuss how the paternity data can be used to differentiate between two mechanisms underlying the expression of alternative reproductive tactics, comprising the condition strategy and alternative strategies.

The proboscis of male elephant seals ( Mirounga Gray, 1827) has been suggested as an example of a secondary sexual trait since Darwin. There has been much speculation about its social function (e.g., optical signal of breeding status, amplification of vocalizations, cue for female choice). However, it has never been studied in detail, probably because its fleshy nature makes measurement difficult. In this paper, we employ photogrammetry to measure the proboscis and facial morphology of a large sample of wild, unrestrained, displaying male southern elephant seals ( Mirounga leonina (L., 1758)). We describe ontogeny and allometry of the proboscis and analyze current phenotypic selection pressures on proboscis traits. We discuss the potential role of the proboscis in optical and acoustic signaling of male resource-holding potential and status. We demonstrate that proboscis size is positively correlated with age and body size independently, and that it is currently under a positive sexual selection pressure when the effect of selection on body size is removed. We suggest that selection on proboscis size is functionally related to the emission of agonistic vocalizations.

Morphometric measurements or biochemical methods are often required to differentiate deer mice, Peromyscus maniculatus (Wagner, 1845), from white-footed mice, Peromyscus leucopus (Rafinesque, 1818), particularly when they are found in sympatry. However, these approaches cannot easily be applied to juveniles, or to degraded or ancient museum specimens. In this paper, we propose a rapid and non-invasive molecular approach to discriminate these cryptic species from one another. This technique relies on species-specific primers designed in the COIII mitochondrial region to amplify fragments of different lengths in each species. The method developed proved useful for the identification of ethanol-preserved, frozen, degraded, or dry museum specimens.

This paper presents the results of observations concerning the phenomenon of parthenogenesis among Euro- pean mites of the suborder Uropodina. An analysis of the sex ratios of 66 Polish species revealed that 18 of them (more than one fourth of the examined species) consisted only of females. The authors observed no significant relation- ship between geographical distribution and the lack of males in the population. Populations consisting entirely of fe- males were observed among widely distributed species as well as among species characterized by narrow geographical ranges. Nonetheless, an increase in the number of parthenogenetic species, especially as a percentage of Middle Euro- pean and Scandinavian fauna, was also discernible. Species that reproduced without males were associated with forest litter and soil, whereas bisexual species "eagerly" inhabited various relatively unstable and temporary microenvironments (for instance, dead wood, birds' or small mammals' nests). The authors aim to define the biological role of occasion- ally appearing males for the species consisting almost entirely of females and discuss ecological and evolutionary as- pects of parthenogenesis in mites of the suborder Uropodina. Resume : Nous presentons nos observations sur la parthenogenese chez les acariens europeens du sous-ordre Uropo- dina. Une analyse des rapports mâles:femelles de 66 especes polonaises indique que 18 d'entre elles (plus d'un quart des especes examinees) ne contiennent que des femelles. Nous n'observons aucune relation significative entre la repar- tition geographique et l'absence de mâles dans les populations. Les populations constituees uniquement de femelles s'observent chez des especes a large repartition geographique aussi bien que chez des especes caracterisees par des re- partitions restreintes. Il y a neanmoins une augmentation du nombre d'especes parthenogenetiques, particulierement du pourcentage d'especes parthenogenetiques, dans les faunes d'Europe centrale et de Scandinavie. Les especes qui se re- produisent en l'absence de mâles sont associees a la litiere et au sol des forets, alors que les especes bisexuelles re- cherchent activement divers microhabitats relativement instables et ephemeres, par exemple, le bois mort, les nids d'oiseaux et les tanieres de petits mammiferes. Nous cherchons a definir le role biologique des mâles qui apparaissent occasionnellement dans les populations constituees a peu pres exclusivement de femelles et nous discutons des aspects ecologiques et evolutifs de la parthenogenese chez les acariens du sous-ordre Uropodina.

Phaeacius malayensis (Salticidae: Spartaeinae) is an atypical jumping spider that routinely includes other jumping spiders in its diet. This paper presents the first detailed study of P. malayensis' prey preferences. Three basic types of tests of prey preference were used: different types of prey were provided on alternate days (alternate-day tests), two types of prey were provided simultaneously (simultaneous-presentation tests), and an alternative prey type was provided while the predator was already feeding (alternative-prey tests). In alternate-day and simultaneous- presentation testing, but not in alternative-prey testing, ( i) P. malayensis preferred spiders (salticids and hunting spiders) to insects; (ii) P. malayensis preferred salticids to hunting spiders; ( iii) these preferences were not exhibited in some paired choices when the background was nonmatching, indicating that visual concealment is important with respect to some, but not all, prey; (iv) P. malayensis' prey preferences were not affected by a prior 14-day period without food; (v) after 21 days of fasting, P. malayensis took different types of prey indiscriminately. The adaptive significance of preferences for particular types of prey is discussed in the context of optimal-foraging theory. Resume : Phaeacius malayensis (Salticidae : Spartaecinae) est une araignee sauteuse atypique qui consomme couram- ment d'autres araignees sauteuses. Les preferences de P. malayensis pour certaines proies sont decrites ici en details. Trois types de tests ont servi a evaluer les preferences : differents types de proies presentes tous les 2 jours (tests des jours en alternance), deux types de proies presentes en meme temps (test des presentations simultanees), ou un type de proie presente alors que le predateur est deja en train de se nourrir (test de presentation d'une proie de rechange). Le test des jours en alternance et le test des presentations simultanees, mais pas le test de la proie de rechange, ont de- montre que (i) P. malayensis prefere les araignees (Salticides et araignees chasseuses) aux insectes; ( ii) que P. malayen- sis prefere les araignees sauteuses aux araignees chasseuses; (iii) que ces preferences ne s'expriment pas lorsque le substrat est contrastant, ce qui indique que le camouflage est important pour certaines proies, mais pas pour toutes; (iv) que les preferences de P. malayensis pour certaines proies ne sont pas affectees par un jeune prealable de 14 jours et (v) qu'apres 21 jours de jeune, P. malayensis consomme indifferemment n'importe quelle proie. L'importance evolu- tive des preferences pour des types particuliers de proies est examinee dans le contexte de la theorie de la quete opti - male. (Traduit par la Redaction) 2226

Sleep is required for the consolidation of memory for complex tasks, and elements of the growth-hormone (GH) axis may regulate sleep. The GH axis also up-regulates protein synthesis, which is required for memory consolidation. Transgenic rat GH mice (TRGHM) express plasma GH at levels 100-300 times normal and sleep 3.4 h longer (30%) than their normal siblings. Consequently, we hypothesized that they might show superior ability to learn a complex task (8-choice radial maze); 47% of the TRGHM learned the task before any normal mice. All 17 TRGHM learned the task, but 33% of the 18 normal mice learned little. TRGHM learned the task significantly faster than normal mice (p < 0.05) and made half as many errors in doing so, even when the normal nonlearners were excluded from the analysis. Whereas normal mice expressed a linear learning curve, TRGHM showed exponentially declining error rates. The contribution of the GH axis to cognition is conspicuously sparse in literature syntheses of knowledge concerning neuroendocrine mechanisms of learning and memory. This paper synthesizes the crucial role of major components of the GH axis in brain functioning into a holistic framework, integrating learning, sleep, free radicals, aging, and neurodegenerative diseases. TRGHM show both enhanced learning in youth and accelerated aging. Thus, they may provide a powerful new probe for use in gaining an understanding of aspects of central nervous system functioning, which is highly relevant to human health.

Bat–insect interactions should be a useful source of case studies for the "arms race" of predator and prey adaptations; currently, well-detailed examples are needed for the formulation of general hypotheses. In this paper I add to information on bat–mantis interactions, testing four predictions of the hypothesis that mantises with ears can detect and avoid bats: that mantises will fly by night, that they will be vulnerable to bats, that echolocating bats will be better at catching deafened than normal mantises, and that mantises which can hear bats' calls will take evasive action. I found that tagged Miomantis cf. natalica Beier flew substantially on dark nights; indoors, undeafened mantises were better at avoiding Rhinolophus clivosus (Rhinolophidae: Microchiroptera) than were deafened mantises (n = 20 pairs; Mann–Whitney test, z = 4.58, p

It is generally believed that predation pressure may drive the evolution of long spines, a robust pelvic girdle, and a deep body in sticklebacks (Pisces: Gasterosteidae). However, the lack of such traits in environments under intense predation pressure suggests that there may be a limit to which these apparently defensive structures benefit sticklebacks. In some environments, well-developed defensive structures may not increase stickleback survival, but may actually reduce fitness if there is a cost associated with them. This paper focuses on a trade-off between defensive morphology and escape-response performance in the brook stickleback (Culaea inconstans). Our study of four populations of brook stickleback reveals that the population with the largest pelvic girdles and deepest bodies has a poorly developed escape response (i.e., small displacement, low maximum velocity, and low acceleration), while the population with the smallest pelvic girdles and shallowest bodies has a highly developed escape response. The two populations with intermediate defensive structures are intermediate in escape-response performance. Consideration of predation regimes in different environments may help us understand selection pressures that favor heavily versus poorly armored stickleback morphs.

The pipefishes (Syngnathidae) are marine teleosts in which the males brood the young. In some species sex-role reversal occurs when, contrary to the usual pattern, females compete more intensely than males for access to mates. This paper reports an investigation of the sex hormones of males and females to see whether they deviate from the "normal" teleost pattern. To that end, plasma levels of the androgens testosterone (T), 11-ketotestosterone (OT), 11β-hydroxytestosterone, 11-ketoandrostenedione, and 11β-hydroxyandrostenedione (OHA), together with 17α-hydroxy-20β-dihydroprogesterone (17,20-P) and 17β-estradiol (E2), were measured by means of radioimmunoassay in three species of pipefish: Nerophis ophidion, Syngnathus typhle, and Syngnathus acus. Plasma levels of OT, the dominant circulating androgen in breeding males of most teleost species, was found to be highest in breeding males and low or non-detectable later in the brooding males. This observed decline in male OT levels from the prespawning to the postspawning (=brooding) period is in general agreement with what has been found in other teleosts. In both breeding and brooding S. acus males, T was quantitatively the dominant androgen, whereas OHA was the major androgen in S. acus females, as well as in the females and breeding or brooding males of both S. typhle and N. ophidion. In breeding S. acus and S. typhle males the levels of T, OHT, and OT were higher than in corresponding brooding males and females. The 17,20-P level was below detection limit. E2 was also usually non-detectable, but was most consistently found in breeding Syngnathus males.

The high cardiac outputs observed in tuna compared with other teleosts may imply differences in the regulation of myocardial contractility. Sarcolemma is a critical organelle in the teleost heart in the regulation of intracellular calcium concentration and hence contractility. A procedure is described for the isolation of large quantities of highly purified sarcolemma from the skipjack tuna heart by differential and sucrose-gradient centrifugation in the presence of multiple protease inhibitors. The preparation was characterized using the sarcolemma marker K+-stimulated p-nitrophenylphosphatase (K+pNPPase). From a starting ventricular wet weight of about 60 g, a yield of > 20 mg sarcolemmal protein and a > 43-fold purification over the crude homogenate were achieved. The percentage recovery of the total K+pNPPase in the sarcolemma fraction was greater than 14%. Both the purification index and recovery were substantially greater than those achieved with a much smaller scale sarcolemma preparation recently described for the trout heart. The equilibrium binding of the dihydropyridine PN200-110 and ryanodine were determined in these preparations. In purified sarcolemma, the dihydropyridine receptor binding density (Bmax) and dissociation constant (Kd) were found to be 0.48 ± 0.07 pmol∙mg protein−1 and 0.09 nM respectively, similar to that found in mammals. In crude homogenates, the ryanodine receptor Bmax was approximately 0.12 ± 0.04 pmol∙mg protein−1 and thus was a little more than half the value observed for the dihydropyridine receptor. The large-scale sarcolemma isolation procedure described in this paper for tuna may be useful for developing a better understanding of the role of the sarcolemma in the regulation of ventricular function in teleosts.

The total number of fibers and the range of fiber diameters in the cochlear nerve of three species of toothed whales were determined. There are 90 672 fibers in Lipotes vexillifer, 82 570 in Neophocaena phocaenoides, and 77 171 in Sousa chinensis. In Lipotes the fiber diameters range from 0.4 to 25.8 μm, with a modal diameter of 9.5 μm, and the largest fiber measures 35.2 μm; in Neophocaena, the diameter ranges from 0.6 to 36.0 μm, with a mode of 9.5 μm, and the largest fiber measures 54.9 μm; in Sousa the diameter ranges from 0.3 to 39.7 μm, with a mode of 8.5 μm and the largest fiber measures 50.3 μm. In Lipotes, Neophocaena, and Sousa, 1.5, 8.5, and 14.2%, respectively, of the cochlear fibers are ≥ 20 μm in diameter. Almost all the fibers are myelinated, and the ratio of the diameter of the axis cylinder to the outer diameter of the fiber in each species averages between 0.6 and 0.7. The high percentage of large fibers and the very wide range of fiber diameters indicate that the odontocete cochlear nerve is specialized for high-speed communication with the brain. The maximum diameters of the myelinated fibers of the cochlear nerve reported in this paper are the largest diameters recorded for the cranial nerve, or any other nerve, among the vertebrates.

Preserved amphisbaenids with fully everted hemipenes are rare and few studies have described these intromittent organs in detail. Some previous descriptions are misleading as they are based on partially everted hemipenes. In this paper the hemipenes of several species of amphisbaenids are described on the basis of gross anatomical, histological, and scanning electron microscopy observations. Study of a series of specimens of Amphisbaena caeca and of A. innocens indicates that many hemipenes were not fully everted during fixation. The typical amphisbaenian hemipenis consists of a main truncus that bifurcates to form two lobes. The distal tips of the lobes may bear fields of lamellae that surround the termination of the sulcus spermaticus. Various regions of the outer surface of the lobes may also bear microornamentation. Some possible roles of lamellae and papillae during copulation are discussed.

A glandular cushion, called the pedal aperture gland in this paper, lies adjacent and internal to each of the two mantle margins composing the pedal aperture of the soft-shelled clam Mya arenaria. Two types of glandular cells are found in the glands. The principal type (bacillary mucous cell) manufactures secretory vesicles that contain discrete protein-rich fibers in a matrix of glycoprotein. The second type (mucous goblet cell) produces sulfated and nonsulfated mucosubstances. The glands function in the formation of pseudofeces from particulate material, especially burrow sediments that enter the mantle cavity through the pedal aperture. Their possible phylogenetic relationship to similar glands in other bivalves is discussed briefly.

This paper surveys the biology of central Amazonian fishes and the physicochemical conditions of their habitats, with particular emphasis on factors related to respiration, in order to place in an ecological perspective the studies of respiratory physiology carried out on the 1976 Alpha Helix Amazon Expedition.The environment is strongly influenced by the annual flood cycle and is characterized by high temperatures and widespread hypoxia. Important differences exist among habitats in the absolute levels and degree of dairy and seasonal variation in temperature and oxygen supply.Air-breathing fishes are numerous and diverse in comparison with other types of aquatic environment, but make up only a small proportion of the total fauna, even in the more hypoxic habitats. Many other species use the oxygenated surface layers for branchial respiration. The potential interrelationships between respiratory strategies and other aspects of the species biology such as feeding niche, habitat type, aniipredator strategies, and capability of overland movement s are discussed.

Using the patency assay for antigonadotropic activity described in earlier papers, the tissues of the ovary are shown to be devoid of antigonadotropic activity, although earlier reports had identified the ovary as the source of the antigonadotropin released by virgin females that had retained their eggs. Using both the patency assay on whole follicles, and an interference microscopy assay on isolated follicle cells, the source of the antigonadotropin has been traced to four pairs of abdominal neurosecretory organs, one pair in each of segments II, III, IV, and V.

The electron microscopic study of several strains of Babesia microti provided evidence that this parasite has two types of organisms in the intraerythrocytic stage. In one, the trophozoites undergo differentiation and reproduce by formation of merozoites. In the other no differentiation or reproduction occurs and the parasites acquire an unusual shape. A hypothesis was put forward that the latter organisms might be gametocytes. This term has been used tentatively throughout this paper. An examination of ticks fed on hamsters' blood infected with B. microti has shown that parasites emerging from hemolyzed erythrocytes closely resemble the intraerythrocytic gametocytes in their shape. A reorganization and differentiation of the cytoplasm expressed in the appearance of new structures occurs. Among them the most striking is a complex organelle that looks like an arrowhead. Several arrowheads are found in a single gametocyte, each marking an incipient gamete. Most gametes are equipped with an arrowhead organelle, a tail, microtubules, and a cytostome. Occasionally a close apposition of two gametes and cytoplasmic fusion between the two organisms was found but it is not excluded that this might represent division. The use of the terms 'gametocyte' and 'gamete' is not yet fully justified. More evidence is needed.

The cyphonautes larva of Membranipora membranacea (phylum Bryozoa, order Cheilostomata) is a laterally compressed, planktotrophic larva covered by a triangular, bivalved shell. In this paper, the general morphology of the larva and the cytology of the body wall and gut are examined by light and electron microscopy. The outer part of the body wall underlying the shell consists of an essentially nonciliated layer, called the aboral epithelium. At the larval apex, the aboral epithelium forms a knob-shaped apical organ. The apical organ contains putative sensory cells, a basal nerve plexus, and a group of undifferentiated epithelial cells that probably corresponds to a blastema. The body wall at the base of the larva constitutes the larval locomotory organ or corona. The corona consists of two rows of multiciliated cells, which are flanked by myoepithelial cells and monociliated cells. A large mantle cavity, referred to as the vestibule, occupies the central region of the larva. The vestibule is partially divided into an anterior inhalant chamber and a posterior exhalant chamber by two ciliary ridges that run along the sides of the mantle cavity. At the base of the larva, the inhalant chamber is surrounded by a horseshoe-shaped flap of tissue, called the velum. Apically, the inhalant chamber forms a densely ciliated preoral funnel. Food particles filtered by the ciliary ridges are conveyed to the larval mouth by cilia in the preoral funnel. The mouth in turn leads into a tripartite gut consisting of an esophagus, stomach, and intestine. Two types of ciliated lining cells occur in the esophagus and stomach. The intestine appears to be lined by nonciliated epithelial cells and empties into the exhalant chamber by way of an anus. Morphological features of the cyphonautes larva are compared with those described for other bryozoan larvae in an attempt to define homologous structures among the various larvae of bryozoans.

This paper describes the energy budget dynamics of adults of the bruchid Pseudopachymerina spinipes (Er.), based on changes in body weight and biomass caloric content, and heat dissipation by respiration, all as affected by age, sex, and temperature. Pseudopachymerina spinipes develops in Acacia caven seeds, consumes its cotyledons, and emerges to mate and oviposit without the need for water or further food consumption. The beetles died when 65% of the energy reserve accumulated as lipid during the larval stage is consumed. This amount of lipid represents approximately 41% of the body mass at emergence. The life-span depended on the rate of body water loss and on the metabolic rate, independent of the initial body biomass. The adults used lipids as a source of energy to support their metabolic activity. Oxygen consumption decreased with age in males, but only at temperatures above 20 °C. Age did not influence respiration in females at the experimental temperatures. Increasing temperature triggered an increase in levels of and individual variability in oxygen consumption. The respiration rate of males was higher than that of females, particularly at 15 and 21 °C. Thus, females live longer than males and longevity is shorter in both males and females during warmer periods.

In Locusta migratoria, the testicular follicle is made on an apical compartment that contains the youngest germ cells and a basal one in which the spermatids differentiate. As soon as it is formed during the fourth larval stage, the latter compartment becomes impervious to exogenous macromolecules. This permeability barrier, which corresponds to the blood–testis barrier defined in mammals, depends on extensive septate junctions. In this paper, testicular follicles were cultured in vivo in adult males known to be free of hemolymphatic ecdysteroids. The permeability of the apical compartment to horseradish peroxidase, used as a tracer, varied as a function of implantation time. This apical compartment became impermeable as soon as the basal compartment cells were postmeiotic. Once implanted into an adult host, a follicle that contained only gonia completed normal spermatogenesis and established a blood–testis barrier, providing a tight compartment in which meiotic processes occurred. Septate junctions developed normally. These results show that ecdysterone controls neither the differentiation of septate junctions nor the establishment of the blood–testis barrier, which appear both to be conditioned by the initiation of meiosis.

The paper describes the polytene chromosomes of Simulium (Ectemnaspis) ignescens from Colombia and compares them with those of a sympatric undescribed species designated Simulium "C." The two species share the entire banding sequence of chromosome arms IS, IL, and IIIS. Their IIIL arms differ by a single fixed inversion, but their second chromosomes exhibit multistep arrangement differences that were not completely resolved. The nucleolar organizer of S. ignescens is in the base of IIIS, that of Simulium "C" in the base of IS. Polymorphisms in IIS of S. ignescens exhibit partial sex linkage; no sex differential segments were demonstrated in Simulium "C." Common autosomal polymorphisms of both species involve preferentially chromosome III. Preliminary studies indicate that the chromosome maps of S. ignescens can serve as standards for other neotropical Simulium Latreille species including the important vectors of Onchocerca volvulus and Mansonella ozzardi.

The shell color and banding polymorphism of the land snail Cepaea nemoralis has been the subject of numerous ecological studies. Evidence is presented in this paper that differences in opioid modulation of thermal responses are associated with this shell polymorphism. It is shown that the effects of the prototypic opiate agonist, morphine, and prototypic antagonist, naloxone, on the aversive thermal ("nociceptive") responses of Cepaea vary with shell banding pattern and thermal micro-habitat. Of the three morphs examined, the shell type (yellow unbanded) with the highest basal response latency and morphine-induced "analgesia" was present at the warmest environmental temperatures, the shell type (yellow two-banded) with an intermediate basal response latency and morphine-induced analgesia was at sites of intermediate temperature, and the shell type (yellow five-banded) with the shortest response latency and lowest morphine sensitivity was present in the coolest micro-habitats. It is suggested that these differences in opioid modulation of thermal responses may contribute to the polymorphic thermal responses of natural populations of Cepaea.

Eighteen pre- and post-rhombencephalic axial isolates from zebrafish, Brachydanio rerio, presomitic embryos divested of epidermis and yolk were maintained in a nutrient medium for 14 days at 24 ± 2 °C. The paper focuses on the differentiation of the notochord and metamerism of axial somites in culture. The technique is proposed as a possible means for studying parameters pertaining to meristic variation in developing fish embryos.

This paper extends the known geographical and temporal distributions of forms of the morphospecies Prosimulium onychodactylum and consequently supplements the study of Newman (L. J. Newman. 1983. Can. J. Zool. 61: 2816–2835). Larvae were collected from 65 sites in northwestern North America, and six forms were observed. Forms 2a, 2b, and 4a/4b were previously characterized by Newman and forms 8, 9, and 10 are described here for the first time. Form 10 may be conspecific with Newman's form 6. Form 9 from the Yukon, with a unique Y chromosome inversion, may be a geographic variant of Newman's form 2. Form 8, characterized by a large chromocenter, is specifically distinct from all other forms. A cytophylogeny is given which indicates the chromosomal relationships among the forms presently recognized.

The paper has two aspects: (1) It describes the salivary gland chromosomes of Prosimulium mixtum, P. saltus, P. approximatum, P. mysticum, and P. rhizophorum of the eastern North American IIIL-1 or mixtum group. The chromosomes of P. fontanum (CIt, IIIL-1) have been described previously. Description of the complement of P. fuscum (IIIL) is included because of the apparent close relationship of that species and P. mixtum. The cytological criteria provided should make possible identification of last-instar larvae of all known species of the IIIL-1 group. (2) The study leads to some inferences regarding evolutionary mechanisms. The centromere region of each of the three chromosomes exists in at least two alternate forms (CIs/CIt, CIIs/CIIi, CIIIs/CIIIi); sex chromosomes may be based on one or the other of the two alternative sequences in CIII, and extra heterochromatin and chromocenters may be present or absent. Contrary to a priori concepts, which visualize restriction of new chromosomal traits to single lineages, virtually all possible combinations of chromosomal traits are observed. This indicates that in this group of black flies long-lived polymorphisms provided the basis for subsequent interspecific chromosomal differentiation.

This paper examines patterns in the linear distribution of helminths in the small intestine of each of 45 scaup. Over all birds, most common species of helminths were found in over half of the small intestine; their distributions overlapped broadly. In individual birds, each species occupied a more restricted, predictable part of the intestine; "core species" (those present in more than two-thirds of the birds) were more evenly distributed along the intestine than expected by chance and occupied almost all of it; "secondary species" (those in one- to two-thirds of the birds) were clumped in anterior and posterior portions of the intestine; and "satellite species" (those in less than one-third of the birds) were randomly distributed. For all common helminths, the range occupied in individual birds was significantly correlated with population size; however, overlap between adjacent species did not increase with increases in their total numbers. The intestinal helminths of scaup belonged to three guilds: small absorbers (paramucosal), large absorbers (mid-lumenal), and trematodes. The interactions noted above occurred both within and between guilds. The overall helminth community in scaup appeared to be saturated with species belonging to the two absorber guilds, but not with trematodes. Communities within individual scaup sampled this overall community and were often unsaturated. We conclude that the core and secondary species of absorbers provide a basic, interactive structure to the overall community and to most of the communities in individual birds. Trematodes and satellite absorber species provide stochastic elaborations.

Previously, L-thyroxine (L-T4) treatment of 16.5-day-old chicken embryos (approximately stage 42) correlated with a precocious increase in prehatching duodenal alkaline phosphatase specific activity. This paper examines the effects of similar L-T4 treatment on ultrastructural differentiation of the absorptive epithelium. White Leghorn embryos (strain Hyline 934F of Gallus gallus) were given 0.1 mL of saline containing 5-μg doses of either L-T4, or D-T4, or saline vehicle alone through windows in the shell. Untreated windowed and intact unwindowed embryos were additional controls. At the time of treatment (16.5 days) and 24, 48, and 72 h later embryos were killed and their duodena were fixed. At least three embryos were examined in each group. Twenty-four hours after treatment stage 43 epithelial cells resembled stage 42 cells. Forty-eight and 72 h following L-T4 treatment stage 44 and 45 embryos showed evidence of increased Golgi and lysosome activity but depletion of lipid droplets and glycogen stores. Control treatments with D-T4 or saline vehicle did not appear to affect epithelial cell ultrastructure as these embryos resembled unwindowed and windowed control embryos at all stages.

The metacercarial stage of Gymnophalloides tokiensis has a mid-ventral pit which was mistaken in the original description for a wide genital pore. The genital pore is small, on the anterior edge of the ventral sucker, and not surrounded by prominent muscle fibers. Other corrections of the original description include paired, compact vitellaria (referred to as Mehlis gland), a bipartite (not globular) seminal vesicle, and an ovary smaller than the testes; no eye spots or a seminal receptacle are present.Yamaguti's (1971) synonymy of Lacunovermis Ching, 1965 with Gymnophalloides is rejected because of the differences in the location and type of genital pore. In contrast to G. tokiensis, both L. conspicuus and L. macomae (Lebour, 1908) Loos-Frank, 1970 have a wide genital pore that opens some distance from the ventral sucker and both ventral pit and genital pore are surrounded by strong muscle fibers.Two of Yamaguti's (1971) footnotes about gymnophallid trematodes are corrected. In my 1965 paper, I did not synonymize Gymnophalloides with Meiogymnophallus but replaced Gymnophalloides as emended by James (1964) with the name Meiogymnophallus. I did not synonymize Gymnophallus oidemiae, now M. minutus (Cobbold, 1859) Bowers and James, 1967, with G. somateriae but regard them as distinct species.

This paper describes and illustrates the behavior of blast cell nuclei recorded by a motion picture camera through a phase contrast microscope. This behavior includes extension and contraction of the nuclei to present the classically accepted patterns of a rounded nucleus at one moment and an elongated often twisted shape a few seconds later. The motion involved is not amoeboid action. The elongated nucleus is not accepted in the literature as a normal pattern of a blast cell nucleus but it obviously should be. After an extension the nucleus contracts again presenting the classical rounded form commonly associated with blast cells.The authors believe that this nuclear behavior is a natural function of the blast cell and that it occurs many times during the life history of this cell. It is especially characteristic of the time when the blast cell is releasing most of its nuclear contents to form free basic nuclear units and other components of the blood. A comparison is made with similar blast cells and their nuclear variations in a Feulgen "gentle squash" preparation which is lightly counterstained with fast green F.C.F.

This paper presents a description of the cells of the normal mesenteric lymph node of the rabbit. The work evolved from a study of the developmental history of the plasmacyte in this organ. The imprint method was used in the preparation of the slides. Several cellular stages not previously recorded in the literature are described.

This paper presents the continuation of studies on blood cell behaviors published earlier by Engelbert.It was then shown that "nuclear bodies" named "basic nuclear units" passed through several stages of a nuclear life history which was believed to hold the key to blood cell cytogenesis. Blood cell polymorphism or pleomorphism is believed to be products of the many staged nuclear life history. The nuclear life history can be experimentally altered, for example by foreign proteins. The basic nuclear units are believed to be reproductive organelles.Additional evidence of nuclear behaviors fitting into the nuclear life history is presented. Formation and release of vesicles by myeloblast nuclei was demonstrated earlier. Evidence is presented here to show that the production and release of these intranuclear vesicles is not a sign of degeneration, but a process by which new cells can be produced through reassociation of released nuclear materials. Some released vesicles become red blood cells. Extreme variations in shape of myeloblast nuclei are not signs of degeneration, but are characteristic nuclear behaviors associated with nuclear activity.The release of new small nuclei, intranuclear vesicles, and various granules are nuclear activities leading to formation of new cells.

This paper reports the continued investigations into nuclear behaviors and activities of blood cells.Further proof of the extreme changes in shape of the almost naked nuclei of blast cells and evidence of the motility of such nuclei are presented. Further evidence for the release of intranuclear vesicles which become red blood cells is given. The cyclic nature of the life history of lymphocytes, which was first postulated in 1956 (Engelbert (5)), is again emphasized, also the extreme changes in morphology of the whole nucleus as well as the basic nuclear units which take place during the life history. The nucleus should be regarded as a federated composite structure—a federate autonomy—made up of smaller structures, the basic nuclear units, that each have a certain autonomous potential, which comes into play when they leave the composite federation. The nuclear federation can become very large forming polypoid nuclei. Naked nuclei can form "cytoplasm" by contracting and thus squeezing nucleoplasm out into a rim around the nucleus.

This paper presents a light microscope study of the cytology of the cells which secrete a substance into the lumen of the spermatheca of Rhodnius prolixus. On the basis of histochemical tests, the material in the lumen appears to be a mucoprotein or glycoprotein. It is suggested that the secretion provides a source of energy for the maintenance of the spermatozoa.

This paper records a discovery of basic, partially independent nuclear units that lie within a common nuclear membrane of some vertebrate cells. The cells concerned are found in series from small (1–2 μ) to large (10–15 μ or more). The smallest cells possess one basic nuclear unit, the larger cells have several. The series of cells from small to large represent stages of a life cycle. Certain of the basic nuclear units act as reproductive organelles and certain large cells are parent cells producing new small cells thus closing one life cycle and starting another. The large cells are formed from the small cells through a series of fusions. The basic nuclear units behave similarly to micronuclei, the reproductive organelles in ciliates, but the fusions of the vertebrate cells are permanent, not temporary unions such as conjugation in ciliates.

In lake chub, Couesius plumbeus, hypophysectomy causes marked regression in the testes, suppresses the mitotic ability of the spermatogonia, completely blocks their transformation into spermatocytes, and affects the normal secretory activity of the lobule boundary cells. Spermatogenesis is largely reinitiated and secretory activity of lobule boundary cells is restored by injections of a partially purified salmon pituitary extract, by mammalian luteinizing hormone, and by crude extracts of whole pituitary of salmon. The gonadotropin responsible for testicular maturation is similar to mammalian luteinizing hormone; a factor like mammalian follicle-stimulating hormone is probably not physiologically active in this fish. Although gonadotropin is primarily responsible for gonadal maturation, other factors such as thyrotropin and somatotropin probably have a stimulatory effect by acting synergistically with the gonadotropin. The paper presents details of a technique for hypophysectomy.

This paper describes a pair of convoluted structures tying on either side of the digestive tract in the mesothorax of Lytta nuttalli Say. They are absent in all the larval stages, but in both sexes of the adults they are equally well developed. They are also found in Lytta viridana LeConte. Each structure has two distal branches ending blindly in the thorax and a short proximal portion leading to an external opening via a prominent reservoir. Histologically they are typically glandular in appearance and show definite indications of secretory activity. They are not thought to secrete either saliva or cantharidin, but rather to produce a pheromone which mediates the formation of protective aggregations of the insects. This type of gland is not known to occur in any other family of insects.