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Larval nematodes identified as Eustrongylides wenrichi Canavan 1929, from cysts in the tissues of Amphiuma means tridactylum Cuvier in Louisana were redescribed. The extent of differentiation of the sex organs was found to be greater than that of 3rd-stage Dioctophyma renale, or of the infective stage of Trichinella spiralis, and comparable with the late 4th-stage larva of secernentean (phasmid) nematodes.

Sporocysts obtained in Singapore in the feces of the boid snake, Python reticulatus, were given by mouth to laboratory rats, mice, and a monkey (Macaca mulatta). Infections developed in rats only. Schizonts were observed in vascular endothelium of various tissues of rats examined at 7 to 15 days of infection; and in each of 20 rats examined at 1 mo to 2 yr, cysts of three species of Sarcocystis were observed. Based on observations made by light and electron microscopy, one species was identified as S. singaporensis and redescribed; two species, S. villivillosi and S. zamani, were described as new. The cyst wall of S. singaporensis is thick with tall, stalked, digitiform villi. That of S. villivillosi is moderately thin and bears short, stout villi that are covered with microvilli; and that of S. zamani is thin and bears delicate, branched villi. The cyst of S. zamani is macroscopic with rounded ends; it induces multiplication of host-cell nuclei and causes resorption of the myofibrils. Cysts of the other species are microscopic with fusiform shape that changes markedly with contraction of the host cell. Refrigerated sporocysts of S. singaporensis, S. zamani, and S. villivillosi remained viable for at least 24, 14, and 6 mo, respectively. Sarcocystis singaporensis and S. zamani apparently have been reported previously from several species of Malaysian wild rodents; S. villivillosi represents a unique type in rodents.

The persistence and precise location of Ancylostoma caninum larvae in tissues of vertebrate paratenic hosts and the nature of host responses were studied in mouse, cat, and monkey. Mice were infected percutaneously and examined at various intervals up to 260 days after exposure. Long-persisting larvae were found only in the muscles. Histologic sections revealed that within 4 hr after exposure some larvae had migrated through the skin and had entered individual fibers of the underlying muscles. After the 1st day nearly all larvae found in muscles were within fibers. Granuloma formation and encapsulation were not observed, suggesting that inside the fibers the larvae produced no direct inflammatory reaction. Only diffuse infiltration of inflammatory cells was observed in muscles and this appeared to be in response to destruction of muscle fibers. Larvae were similarly located in muscles of a cat and a rhesus monkey examined 16 and 17 days, respectively, after cutaneous exposure. The histologic changes observed in muscle fibers invaded by A. caninum larvae are similar to those observed in early Trichinella spiralis infections. The larvae of A. canninum lying coiled within the muscle fibers also bear superficial resemblance to the larvae of T. spiralis. A. caninum larvae were also recovered by tissue digestion from muscles of naturally infected dogs, which suggests that larvae reside in this location in the bitch prior to transfer to the neonate via the milk.

Thirty or more microfilariae 0.70-1.32 mm in length were recovered from the hemocele of an unengorged adult tick, Ixodes dammini, that was collected from vegetation on Shelter Island, New York. Among approximately 500 I. dammini collected from the same area only 1 other was similarly infected. Outstanding features, in addition to size, were absence of a cephalic space and the presence of nuclei in 2 or 3 irregular rows extending to the end of a bluntly rounded tail. The microfilariae apparently were ingested in a blood meal that was taken when the ticks were larvae or nymphs, and had persisted alive without development.

Rules of stress like those described by Chomsky & Halle 1968 are examined for their relevance in determining metricality (using Halle & KCeyser's [1966] stress maximum concept) over the period of modern English. The Nuclear Stress Rule frequently locates stress maxima in unmetrical positions, and the Compound Rule occasionally does. A late, optional rule is proposed-the Stress Exchange Rule-which reverses unmetrical alignments resulting from earlier rules. An Alternating Stress Rule is also proposed, to account for non-lexical stress. Thus stress maxima are created in different ways. The possible rule combinations (lexical, phrasal; obligatory, optional) discriminate degrees of metricality, and provide stylistic parameters.

In regions of the United States where ascariasis is most prevalent, hookworm (Necator americanus) infections are uncommon or absent. Conversely, in regions where hookworm infection is hyperendemic, as in the lower coastal plain of the southeastern United States, the incidence of ascariasis is generally low. Clay and other types of dense soils which predominate in ascaris areas are known to be unsuitable for the development of infective hookworm larvae and thus constitute one of the principal limiting factors (Augustine and Smillie, 1926; Rickard and Kerr, 1926). The factors responsible for the low incidence of ascariasis in regions where conditions are favorable for hookworm infection have not been well established. The

A little over a decade ago not a single life history was known for North American trematodes and up to the present time only ten, none of which concern amphistomes, have been experimentally established. An amphistome life history is here demonstrated through a study of larval and adult forms collected from the Ox-Bow, northeast of Urbana, Illinois. A cercaria from Planorbis trivolvis was found to encyst on crayfish and frog larvae, and when fed to bullfrogs (Rana catesbiana) and snapper turtles (Chelydra serpentina) developed into a known species, Allassostoma parvum Stunkard 1916. The extraordinary size of the terminal organs of the excretory system of the redia stimulated intensive studies on this system in both redia and cercaria stages. Sincere thanks and appreciation are here extended to Professor Henry B. Ward whose guidance and criticisms have made this work possible.

In October, 1939, 12 of 39 Stagnicola palustris elodes (Say) which were collected in a marshy area near Black Creek, Wisconsin, were infected with a species of large echinostome cercaria. It was found that the metacercaria would develop in various species of pulmonate snails, and with further collections in the fall of 1940 and in 1941, the adult stage was cultured in young albino mice. In October, 1941, 6 adult worms were taken from the lower ileum of a field host, Porzana carolina (L.). With a description of those examples from the field host, the study was concluded and a manuscript was nearing completion when a paper by Feldman (1941) was published on the morphology and life cycle of the same species. Comparison of the two studies revealed minor points on which observations differed, and some additional data which Feldman's paper did not contain. The purpose of the present report is to record these supplementary data. The cercaria which Feldman obtained from Stagnicola reflexa was declared to be identical with Cercaria reflexae Cort, 1914, and the adult which was obtained from experimentally infected chicks was thought to be a member of the genus Psilostomum Looss, 1898. Thus this species was introduced into the literature as Psilostomum reflexae. For several reasons to be discussed later, mainly because of its crown of spines, this species cannot be a member of the genus Psilostomum. It represents instead a new genus. Also, there is no justification for declaring the cercaria identical with C. reflexae Cort. It resembles C. reflexae but differs from it markedly, especially in size and spination. For Psilostomum reflexae, the new name Protechinostoma mucronisertulatum, n. g., n. n. is proposed.

A MONG ANIMALS in general there is a wide variety of parasitic infections in which larval stages migrate through and sometimes later reside in the tissues of the host without developing into fully inature adults. When such parasites are found in human hosts, the infection may be referred to as larva migrans although definition of this term is becoming increasingly difficult. The organisms implicated in infections of this type include certain species of arthropods, flatworms, and nematodes, but more especially the nematodes. As generally used, the term larva migrans refers particularly to the migration of dog and cat hookworm larvae in the human skin (cutaneous larva migrans or creeping eruption) and the migration of dog and cat ascarids in the viscera (visceral larva migrans). In a still more restricted sense, the terms cutaneous larva migrans and visceral larva migrans are sometimes used to denote the formation of lesions due to a particular species of larva known or presumed to be the one most commonly involved: Ancylostorna braziliense in the skin, and To/xocara canis in the viscera. This usage of the terms is incorrect, however, since, as previously emphasized, the character and location of the lesions and the resultant symptoms are unreliable clues in the specific identification of the causative organisms (1).

The Harada-Mori type of hookworm culture which consists of a thin film of feces on a strip of filter paper in an upright test tube containing a shallow reservoir of water was found to be a simple and effective medium for incubating Spirometra and Paragonimus eggs. When the eggs of S. mansonoides in feces of experimentally infected cats were cultured by this method, essentially all of the eggs contained coracidia in 2 weeks at room temperature (22 to 26 C). When the feces-smeared filter paper from the culture was placed in water, there usually was prompt hatching and swarming of coracidia into the water. Eggs of P. kellicotti similarly incubated in feces of an experimentally infected cat contained fully developed miracidia in 17 to 20 days and these remained viable in cultures for 3 months. When placed in water, a high proportion of the miracidia hatched, especially if subjected to a sudden change of temperature. Hatching in water possibly was not necessary for infecting snails, however, for of 67 Pomatiopsis lapidaria allowed to feed directly on the leached culture feces, six became infected and shed cercariae in 60 to 68 days. The observations suggest that development of the eggs of these helminths may occur under nonaquatic natural conditions similar to those provided by the Harada-Mori culture. In the laboratory, the eggs of trematodes and cestodes having aquatic intermediate hosts usually are incubated in water. In nature, the infection of such hosts by miracidia and coracidia generally is believed to occur only in aquatic habits. However, the final hosts of many of these parasites frequently-more often than not in some instances-defecate at the water's edge rather than in the water, and a high proportion of the egg-bearing feces therefore rests on and becomes a part of the damp soil at the margin of streams and other bodies of water. Moreover, the intermediate hosts are in some instances amphibious-as, for example, those of Paragonimus kellicotti and Schistosoma japonicum--or are adapted to temporary ponds and to bodies of water having widely fluctuating water levels-as, for example, those of Fasciola hepatica, Fascioloides magna, and Schistosomatium douthitti. Under these conditions the intermediate hosts and the developmental stages of the parasites are for relatively long periods of time in or on the mud and wet ooze of nonaquatic habitats. The type of fecal culture described by Harada and Mori (1955) provides a habitat which in a number of respects resembles those of the mud-ooze situations just referred to. As a preliminary investigation of the possibilities of nonaquatic incubation of eggs and of subsequent natural infection of amphibious and aquatic hosts in and out of water the following observations were made.

Three hundred fifty-eight female Ascaris lumbricoides-258 from pigs and 100 from children-were examined with reference to the presence or absence of a genital girdle in relation to the type of eggs and presence of sperm in the uterus. There was a striking (81%) coincidence of infertile eggs in the uterus and the presence of a girdle. Usually when fertile eggs were in the uterus, either the girdle was lacking, or abundant spermatozoa were in the uterus, attesting to a recent copulation. The observations suggest that the genital girdle forms under the stimulus of a diminishing store of sperm or an increasing number of infertile eggs in the uterus, and is, therefore, an indication of readiness to mate (estrus). Early descriptions of Ascaris lumbricoides usually mention that a constriction of the body is or may be present at the level of the vulva. Leuckart (1876: 196) stated that one occa- sionally sees newly mated females which dis- play at the level of the vaginal orifice a saddle- shaped depression testifying to the strength of the male worm's embrace. In more recent descriptions Leuckart's statement has been variously paraphrased, although in some in- stances it is stated or implied that a girdle is invariably present, and in others reference to a genital girdle is omitted altogether. Omis- sions probably are attributable to the fact that more often than not the genital girdle is inapparent or lacking, and the conditions under which it may be present or absent have not been determined. In fact, mating of A. lumbri- coides is infrequently seen and the mechanism of copulation is imperfectly known (Mueller

It has been shown that estimates of hookworm burden can be based on egg counts in direct fecal smears that are made to a uniform density (turbidity) by means of a photoelectric light meter (Beaver, 1949). As originally described, the method is lacking in two respects. Because photoelectric light meters are manufactured in various models and patterns and, therefore, require diverse types of adapters, the standardization of smears requires a reliable method of calibrating the meter assembly; and since the meter may deteriorate or become damaged, some means of checking its accuracy from time to time is needed. The other obstacle to the general application and usefulness of the method is the lack of standardized smears offering a range of densities suitable for diverse needs and preferences. Both problems are dealt with in this study.

By oral inoculation of juvenile or adult worms, unisexual or bisexual Ancylostoma caninum infections were established in 39 young dogs. Less than 100 adult females caused rapid blood loss and anemia in two dogs at the time when the worms began laying infertile eggs. Equally heavy all-male or balanced male-female infections did not cause detectable anemia. A higher percentage of males remained in recipient dogs when transferred with (62%), than without (49%), females, but females became established equally well with or without males (average 55%). The average rate of laceration (per 100 worms) was greatest in all-female (147) and unbalanced infections (97 and 134), least in all-male infections (21), and relatively low but highly variable in balanced infections (57, range 3 to 122). Laceration rate was not related to overall population density, but when worms were very unequally distributed as they often were in all-female infections, or bunched as they were when males congregated around receptive females, the focal laceration rates were high. Blood in the worm's intestine was evident more frequently in females than in males, being seen in 53, 64, and 80% of females in balanced, unisexual, and unbalanced infections, respectively. The corresponding rates for males were 26, 9, and 37%. More than half of the worms of both sexes were unattached to the intestinal mucosa when observed 15 to 30 min after death of the host through Nembutal injection into the heart. The observations suggest that the female of A. caninum normally mates at intervals of 3 weeks or less, that mating behavior is attendant with laceration of the intestinal mucosa, especially when the sexes are highly unbalanced, and that mating may rank high among those activities of the hookworm which cause blood loss and anemia in the host. It is generally accepted that hookworms cause anemia and that the anemia results directly from blood losses caused by the worms. In the freshly opened intestine of infected dogs, blood is often seen oozing from the lacerated mucosa and filling the intestine of the hookworms. Estimates have been made of the amounts of blood passing daily through the intestine of hookworms (Wells, 1931) and the daily losses of blood into or from the intestine of the host (Roche, 1957a, b; Foy et al., 1958; Clark et al., 1961). The rate of blood loss and the consequent anemia are, in general, proportional with the number of worms present in the intestine. In extreme cases this relationship is clear and indisputable. In some instances, however, the Received for publication 6 December 1963. * Supported by Grant AI-04919 from the National Institutes of Health, U. S. Public Health Service. t Department of Medical Zoology, Kyoto Prefectural University of Medicine, Kawara-machi, Kamikyo-ku, Kyoto, Japan. relationship between worm burden and blood loss or anemia is not evident, and the lack of such a relationship cannot always be explained on the basis of duration of infection or nutriional status of the host (Foy and Kondi, 1960, 1961). The present study was undertaken to examine the possible role of sex and mating behavior of Ancylostoma caninum in the causation of blood loss in the dog. MATERIALS AND METHODS Thirty-nine mongrel dogs 3 months to approximately 6 months of age were caged separately, given a ration of commercial canned dog food, treated for helminths until stools were negative (by zinc sulfate flotation) for a period of at least 15 days, and given infections with adult or adolescent worms of predetermined number and sex. Adult worms carefully removed from freshly killed, naturally infected dogs, or adolescent worms 7 to 11 days of age, similarly taken from experimentally infected dogs, were examined individually under suitable magnification to determine the sex. Counted numbers of the worms were then transferred to 1-ml gelatin capsules and placed over the glottis of a recipient dog. Usually the capsules were