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Discrete traits are of increasing interest in comparative skeletal biological research. Characteristics justifying their use have been investigated primarily in mice, however. Using 72 discrete variants, 321 human skulls from the Terry Collection of known race, sex and age have been studied. Significant sex and age differences were detected. Inter-trait correlation was found to be at a low but significant overall level. Multivariate comparison with conventional craniometric analysis was undertaken on subdivisions of the sample, and distance based on metric and nonmetric data were concordant. It is concluded, on the basis of these findings and the discontinuous variant frequency distributions, that discrete traits in isolation are not of paramount value to skeletal genetic studies, but may be vital in comparison and conjunction with other types of data in analyzing the population genetics of extinct groups.

Hemoglobin I is an uncommon hemoglobin variant in which the lysine residue at position 16 of the a chain has been replaced by glutamic acid. Lysine is the invariant residue in all myoglobin and hemoglobin subunits that have been sequenced, with the exception of the hemoglobin of the lamprey. Replacement of invariant residues is generally reflected in altered functional properties of the hemoglobin molecule and such invariance may be indicative of a unique functional role. However, a study of the oxygen equilibrium and kinetic properties of hemoglobin I showed the functional properties of this hemoglobin to be indistinguishable from those of normal adult hemoglobin.

The three-dimensional structure of antibody and its fragments has been the subject of several recent crystallographic studies. The determination of 6 A resolution of the structure of a myeloma protein [l] was followed by high resolution studies of a BenceJones dimer [2] and Fab fragments [3,4]. These latter studies [2-41 have demonstrated the independent folding of domains along the polypeptide chains [S] at least for the Fab fragment. We have recently reported the structure of a crystalline variable domain from a Bence-Jones protein REI [6] for which the complete amino acid sequence is known [ 71. In section 2 of this communication we outline some of the features of this structure. It seems likely that the observed structural homology between variable (V) and constant (C) domains in the Fab fragment [2,3] is extended to the Fc fragment. Studies of such homology can be made using the Rotation Function [B]. The results given in section 3 indicate a molecular symmetry for

A Markov process (chain) of gene frequency change is derived for a geographically-structured model of a population. The population consists of colonies which are connected by migration. Selection operates in each colony independently. It is shown that there exists a stochastic clock that transforms the originally complicated process of gene frequency change to a random walk which is independent of the geographical structure of the population. The time parameter is a local random time that is dependent on the sample path. In fact, if the alleles are selectively neutral, the time parameter is exactly equal to the sum of the average local genetic variation appearing in the population, and otherwise they are approximately equal. The Kolmogorov forward and backward equations of the process are obtained. As a limit of large population size, a diffusion process is derived. The transition probabilities of the Markov chain and of the diffusion process are obtained explicitly. Certain quantities of biological interest are shown to be independent of the population structure. The quantities are the fixation probability of a mutant, the sum of the average local genetic variation and the variation summed over the generations in which the gene frequency in the whole population assumes a specified value.

The three characters, plant weight, amount of nuclear DNA, and h (hairless septa), in which heritable changes have been induced by the environment, are associated in their induction, in inheritance and in crosses, but the association is not complete. In the F2, h is associated with plant weight in the direction of linkage while a flower colour mutation, w, obtained by irradiating plants with Co60, is associated with plant weight in the opposite direction to linkage. Although h and w segregate independently the amount of “positive linkage” of h with plant weight is inversely related to the amount of “negative linkage” of w with plant weight in the particular environments and crosses used. The three environmentally inducible characters are unstable in the F1 and none of the genetic variation in F2 need be due to classical segregation or recombination. It is probable that they and w are on the same chromosome and that changes in amount of DNA, which it is supposed are due to changes in number of reiterated sequences, alter the heterochromatisation or structure of the chromosomes and the activity of genes in the region. In heterozygotes the stable equilibria of the homozygotes are destroyed, the induced differences in heterochromatisation of the homologous chromosomes are disrupted giving heterochromatisation of sub-regions, or different amounts of reiteration, whose locations depend upon the intracellular environment.

When the complexity of a developmental system evolves to a certain point, appreciable variation must occur in the process. The problem the biologist faces is whether this point constitutes a limit to the evolution of complexity in developmental systems. If not, what mechanisms are employed to cope with the problem ? The problem—essentially one in “custom fitting” of parts, — and the possible solution(s) to it that have evolved are discussed. The antibody producing system appears to be one that “solves” the custom-fitting problem.

Variations in logistic growth curve among rice varieties were investigated using dry-mat-ter weight data from the International Rice Adaptation Experiment. Two major trends of variation were detected, one represented by the developmental stage at which growth rate beco-mes maximum (variation betweeh early- and late-vigor types), and the other represented by the durability of high growth rate (between sustained- and dash-vigor types). These varia-tions were found to be controlled by varietal genotypes. Early vigor contributes to the production of many spikelets, while late vigor contributes to the growth after heading and filling the spikelets with grain. Sustained-vigor types gave more grain yield than dash-vigor types. The pattern of changes in these vigor types due to fertilizer application also appeared to be varietal characteristics.

The genetic control of plant height was studied in crosses of four spring wheats involving the standard height variety Ramona 50 and short-statured selections Olesen, D6301, and D6899. Data from parent, F1, F2, and F3 populations indicated that four independently segregating loci account for most of the differences among the four varieties. Two major genes of a highly recessive nature condition reduced height in Olesen and the Norin 10 derivative D6301. Olesen also carries a third dwarfing gene which is partially dominant in its effects over genes for tallness. This gene, or a gene that acts in a similar manner, is also present in the standard height variety Ramona 50. Dwarfing in D6899, a derivative of Tom Thumb, is controlled primarily by a single gene with mainly additive effects which is not present in any of the other three varieties. Genetic components estimated from generation means (parental, F1, F2, F3, and backcross) indicated that additive gene effects were the major component of variation in four of the six crosses, and of similar magnitude to dominance effects in another cross. The primary source of genetic variation in the cross Olesen × D6899 was due to epistasis with both additive × additive and dominance × dominance effects of major importance. The results of the generation mean analyses were consistent with the models for major-gene control of plant height based on segregation patterns.

A pedigree control line of mice (ICR stock) with a mean effective population size [Formula: see text] of 110.52 was evaluated over 26 generations. Control lines, sampled from the ICR stock, of 16, 8, 4, 2 and 1 pairs, replicated 2, 2, 4, 8 and 16 times, respectively, were maintained for 15 generations. Mean inbreeding coefficients (F) were 0.10 in the ICR stock and 0.12, 0.20, 0.42, 0.76 and 0.95 in the respective control lines. Traits evaluated were per cent females littering (PFL), number born (NB), 12-day litter weight (W12), body weights at 3 (WK3), 6 (WK6) and 8 (WK8) weeks, gain from 3 to 6 weeks (PWG) and 6-week tail length (TAIL). The significant (P etended to show greater average divergence among replicates. For about 70% of the Ne-trait combinations the observed variance among replicates exceeded the predicted drift variance. Linear regressions of control line means for each trait on F, within generations, were significantly (P

Adult male mice were given gonadal doses of 0–1200 rad acute X-irradiation and mated the same day. 531 sons, conceived within a week of the treatment, were tested for fertility and their testes examined cytologically for chromosome aberrations in spermatocytes. 55 57 of those diagnosed as semi-sterile and 35 40 of those diagnosed as sterile were judged to be heterozygous for one or more reciprocal translocations. Numbers of 0, 1, 2… translocations per mouse showed a good fit to a Poisson distribution, in contrast to previous findings with spermatogonial irradiation. Although the dose response fitted a linear relationship, the power law equation of best fit had a dose-exponent of 1.41. Further analysis along similar lines to those used previously in Drosophila by Catcheside, Lea and Haldane , which assumed random rejoining of breaks and direct proportionality between dosage and number of breaks, gave a close fit between the actural results and those expected if αq = 2.8·10 3− /rad, where α is the mean number of breaks per nucleus and q is the proportion which rejoin or restitute. By combining these data with those for litter-size reduction in F 1 (taken as a measure of induced dominant lethality) α was estimated to be 3.4 × 10 −3 per rad. When compared with the value of 0.8 × 10 −3 per rad obtained in Drosophila by Haldane and Lea , this suggested that mouse haploid nuclei are more radiosensitive to chromosome breakage than Drosophila haploid nuclei by a factor of about 4. The mean number of implants per pregnant female mated to cytologically abnormal males was about 15% lower than with normal males. This pre-implantation loss was thought to be mainly the result of a reduction in the rate of fertilization in this group rather than to early death of unbalanced zygotes. There was no evidence for the induction of any undetected types of chromosomal aberration or gene mutation which could cause intrauterine death in the progeny of F 1 males.

Tissue-cultured Aedes albopictus cells infected with morphologically homogeneous Sindbis virus were found to produce progeny virions which could be divided into three classes based on size. The thickness of the envelope was constant on all three sizes of progeny virions suggesting that the variability in size rested with the viral nucleocapsid. It is suggested that the three classes of virions have icosahedral nucleocapsids composed of common subunits organized in decreasing triangulation numbers.

A new inherited variant of α1-antitrypsin (protease inhibitor or Pi) has been found in five individuals of a family of Welsh origin. The new allele is called PiN, as the α1AT product migrates in acid starch gel between the products of the PiM and PiP alleles. The individuals carrying the PiN allele are all of Pi type MN. The new variant has been compared in several electrophoretic systems with other variants migrating in a similar region by acid starch gel electrophoresis (M, P, S, V, W and X). Acid starch gel and crossed antigen-antibody electrophoresis are most suitable for distinguishing the PiN product. By immunofixation electrophoresis, N has a mobility only slightly different from that of M, however the value of this method can be seen for distinguishing other slow variants which cannot be clearly distinguished on acid starch gels. Twenty-three variants of α1AT are now known. Twenty-two of these are electrophoretic variants and one, the null allele (Pi−), produces no α1AT.

Our objectives were to estimate genotypic and environmental variances and heritability of indole alkaloid concentration in reed canarygrass (Phalaris arundinacea L.) The variance component estimates for genotype ✕ environment and genotype ✕ cutting interactions were significant but small as compared to the estimate for genetic variance among 31 unrelated clones of diverse origin. Genotype ✕ environment ✕ replication in environments interactions were statistically nonsignificant. Thus, variation in alkaloid concentration was largely associated with genotypes. Heritability studies included 36 clones and their 18 two-clone crosses grown at 2 locations. Heritability estimates from the second cutting were higher than corresponding estimates from the third cutting. Combining data from two regrowth cuttings in one season reduced the bias introduced as a result of sampling the forage at different growth stages. When based on parents in the 0.17 to 1.37% overall alkaloid concentration range, realized heritability estimates for the combined August and September cuttings ranged from 0.67 to 0.72. All heritability estimates were slightly higher for the high alkaloid concentration range compared to estimates for the low range. Narrow-sense heritability estimates were nearly as large as the corresponding broad-sense estimates; thus, total genetic variance was largely additive. Parent-offspring regression analyses of identical materials confirmed this conclusion. Our results suggest that genetic gain in alkaloid concentration can be realized from selection among individual plants.

The frequencies of electrophoretically distinguishable allelic forms of enzymes may be very different from the corresponding frequencies of structurally distinct forms, because many sequence variants may have identical electrophoretic charge. In large populations such frequencies will be determined largely by the number of amino acid sites that are free to vary. The number of distinguishable electrophoretic variants will remain fairly small. Beyond some limiting size, no further effect of population size on allele frequencies is expected, so isolated large populations will have closely similar allele frequencies if polymorphism is due largely to mutation and drift. The most common electrophoretic alleles are expected to be flanked by the next most common, with the rarer alleles increasingly distal. Neither strong selection nor mutation/drift interpretations of enzyme polymorphism are yet disproven, nor is any point between these extremes.

The effects of different intensities of single trait directional selection on the heritability and genetic correlation of two quantitative traits in random mating populations of mice were observed during 14 generations. The initial population was divided at random into five groups (A, B, C, D and E). Group A and Group B were under 30% and 60% mass selection for large 6-week body weight, respectively. Group C and Group D were under 30% and 60% mass selection for long 6-week tail length, respectively. Group E acted as control group with no selection applied. In all groups, the parent population consisted of 15 males and 30 females each generation, mated at random.Direct selection had no apparent effect on the heritability of either the trait under selection or the correlated trait over the 14 generations. Heritability of 6-wk tail length was higher than the heritability of 6-wk body weight. Estimates of heritability of 6-wk tail length ranged from 0.15 ± 0.22 to 0.68 ± 0.24, while estimates of heritability of 6-wk body weight ranged from 0.05 ± 0.17 to 0.33 ± 0.09. There was no significant difference among the estimates of genetic correlation between the two traits in the five selection groups. Estimates of realized genetic correlation between 6-wk body weight and 6-wk tail length seemed to indicate that more intense selection led to some decrease in genetic correlation between the two traits.

Selection of stable variants, nonsensitive to horse serum inhibitors, was achieved by growing influenza A (H3N2) strains, originally sensitive, in the allantois-on-shell system with incorporated normal horse serum. Most of these variants, when compared to their respective parental line, showed a greater eluting activity not related to a greater enzymatic activity. Investigation of the ability to agglutinate erythrocytes from different animal species and the thermostability of the hemagglutinin and the neuraminidase did not reveal a complete correlation between these markers and resistance to horse serum inhibitors. When applied to known attenuated strains, also nonsensitive, these same markers could not be linked directly to the attenuation of these viruses for man.

Approximate conditions for genetic polymorphism in temporally and spatially varying environments are presented for loci which are intermediate at the level of fitness or at the level of gene function. The conditions suggest that polymorphism will be more likely in more variable environments while unlikely in constant environments. Biochemical evidence is presented to justify the assumption of heterozygote intermediacy. Observations on natural populations are cited which substantiate the claim that allozymic polymorphism is primarily due to selection acting on environmental variation in gene function.

The level of redundancy of ribosomal genes, and the relationship of this level to nucleolar formation at different stages of embryonic development, have been examined in the Mexican axolotl, Ambystoma mexicanum. Individuals from 4 inbred stocks were examined, as well as descendants from 2 nucleolar variants which, in the heterozygous condition, are distinguished by exceptionally small nucleoli. Ribosomal RNA-DNA hybridization assays show that one of the 4 wild type lines has only about one-third as much ribosomal DNA (rDNA) as the other three. One of the nucleolar variants has the same level of rDNA as the larger wild-type level; the other variant has the same amount as the smaller ribosomal genome line. Both original nucleolar variants arose as F1 progeny of crosses between a large rDNA genome line and the small genome line. Cytological examination of pregastrula stage embryos from wild type and nucleolar variant lines show that the lengths of the nucleolar organizer regions (NOR) and the sizes of nucleoli formed, are directly correlated with the amount of rDNA present at the nucleolar locus. During gastrulation of the nucleolar variants, however, a transition appears to take place and the amount of rDNA ceases to be the determining factor in nucleolar size. After late gastrula, heterozygous progeny resulting from crosses of either large rDNA genome or small rDNA genome wild type individuals with either nucleolar variant line, have a small and a large nucleolus. The factor or factors associated with this apparent lack of competitive ability of the variant NOR, when opposed to a normal NOR, are unknown. It might be suggested that since the chromosomal alterations which produced the nucleolar variants in both cases eliminated the gene determining the dark colour pattern, they could at the same time have eliminated other genetic material.

Two selection experiments comparing the relative efficiencies of individual, family, and combination selection were conducted. The expected results for larval weight of Tribolium (h 2 = 0.20) and for pupal weight (h 2 = 0.40) were that combination selection would be a more efficient method than family selection, and that family selection would exceed individual selection. In experiment I, individual selection produced more response (P < 0.05) than did combination or family, which was not in agreement with expectation. There was confounding of inbreeding levels and random drift due to differential effective population sizes in the lines selected by different methods. Experiment II consisted of ten single-generation selection tests. An advantage of this approach is that it eleminates the inherent problems of differential inbreeding levels and differential rates of genetic drift due to unequal population sizes among the methods of selection. There were no statistically significant differences in efficiency among the three methods of selection for both traits. This was contrary to theoretical expectations but does suggest that with traits of 20% h2 or higher, and where feasible, one may be justified in basing selection decisions on the phenotype of the individual only. Other advantages of single generation testing are that it allows more precise testing of selection theory and unbiased standard errors for estimates of realized heritability.

The flagella of the motile sperm cells of Nymphon leptocheles and N. rubrum (Pyonogonida, Arthropoda) exhibit a 12+0 and a 9+0 axoneme pattern, respectively. Central tubules, central sheath, spokes and arms are absent. The doublets are connected by a circular nexus. The functional significance of this axonemal composition is discussed. Aberrant axonemes occurring in high frequencies both within the species and within single specimens are probably explained by the loose axonemal connection, due to the absence of a central complex. This absence is further suggested to have facilitated the evolution from the 9+0 type to the 12+0 type.

Responses to selection for high and low pupal weight in Tribolium castaneum under four different inbreeding systems and two different relative humidities (40 and 70%) were observed for seven generations. By the seventh generation, the coefficients of inbreeding ranged from 0.79 in the full sib lines to 0.12 in the control lines.Heritability of pupal weight estimated by mid-parent offspring regression from the base population was around 0.30 which is lower than the estimates obtained by Bell (1969). However, realized heritabilities were around 0.50. Significant progress was observed for both upward and downward selection. A linear response in pupal weight was observed for most of the selected lines, suggesting that the selection limit had not been reached.Inbreeding caused a reduction of approximately two offspring per 10% increment in the inbreeding coefficient.Asymmetric responses were noted in conjunction with the significant interaction of the degree of inbreeding and the direction of selection.

An abnormal prothrombin variant, Prothrombin Barcelona, has been isolated by chromatography on DEAE Sephadex, from several members of the same family. In the absence of any normal component, it was eluted in two unequal peaks. The second peak was homogeneous. This component had the same molecular weight as normal prothrombin but migrated slightly faster on disc gel electrophoresis. The first peak, the smaller one, was heterogeneous: in addition to a minor band similar to that of the second peak, a major one with less anodic mobility and with a molecular weight of 32,000 was found. A possible chromatographic artefact has been eliminated. The family study gave good arguments for an heterozygote state of both parents, the siblings being homozygote.

SUMMARYSelection for high and low growth-rate was carried out during eight generations of asexual propagation by zoospores and seven generations of sexual reproduction by oospores. The fungus has previously been shown to be diploid during its vegetative phase. In the zoospore lines there was no significant variation and no response to selection, except for the occasional appearance of fast-growing sectors. A high line was established from such a sector; in its sexual progeny the inheritance of growth-rate was non-Mendelian. Propagation through self-fertilized oospores released very considerable genetic variation, and both high and low lines responded to selection. At first the variation within families, and the response to selection, increased with succeeding generations, despite the intense inbreeding. In later generations the high line became less variable, and the progeny oospore cultures resembled the fast-growing sectors. It is concluded that growth-rate is controlled by a polygenic system and by cytoplasmic determinants, a mutant form of which is responsible for the fast-sectoring phenotype.

Summary Genetic transformation of an mRh/2 strain with the DNA from a donor mR/3 strain was examined. Both the strains were ultraviolet-induced mutants of Rhizobium leguminosarum , the donor ( PRI ) bearing markers resistant to penicillin, radiation (UV), and isonicotinyl hydrazide, and the recipient ( pri ) bearing the corresponding sensitive markers. The maximum competence of the recipient cells for transformation was found at the early log phase, and the number of transformations showed a linear relationship to the transforming DNA concentration. The transforming ability of the donor DNA was completely inactivated by heat, ultraviolet irradiation, and DNAase treatment. Six transformants were examined in detail for their biochemical properties and symbiotic efficiency.

Growth of Proteus mirabilis harboring R100-1 ( fi + drd str r cml r tet r sul r ) factors in Penassay broth containing sodium dodecyl sulfate (SDS) leads to the loss of all or part of the genetic elements in high frequencies. In media containing SDS at concentrations as low as 0.03%, both lysis of R + cells and elimination of the R factors occur at high frequencies. Appearance of drug-susceptible cells in R + cultures occurs during the exponential phase of growth; however, the frequencies of susceptible cells increase substantially after the culture reaches the stationary phase. Reconstruction experiments, coupled with other observations, suggest that the major factor in altering the frequency of drug-susceptible variants is the greater resistance of the variants to the lytic action of SDS. This resistance correlates in most cases with the loss of the transfer functions in the resistance transfer factor.

Rabbit alveolar macrophages can induce the L-phase of Listeria monocytogenes in vitro. Microscopic examination of Listeria-infected cultures revealed the presence of intracellular wall defective variants. Isolation techniques using saran membranes yielded L-phase variants which exhibited typical L-form colonies on osmotically protected medium. All attempts at reverting the isolated L-phase have been unsuccessful.

A membrane filter technique using black membrane filters, MacConkey agar and fluorescence under ultraviolet (UV) light was investigated for the quantitative isolation of Pseudomonas aeruginosa from swimming pools. Three thousand four hundred forty-five samples were collected from public swimming pools and enumerated by this method over a 6-month period. Fluorescent cultures were isolated from 222 specimens. Seventy-seven of these fluorescent cultures were selected for biochemical screening, with 75 (97%) being verified as P. aeruginosa . To further assess the specificity and sensitivity of this UV screening technique, a comparative study was made of some morphological and biochemical characteristics of fluorescent pseudomonads obtained from different sources. The sensitivity of the method was unimpaired by either colony types or biochemical variations of P. aeruginosa . The failure of the other two fluorescent species, P. fluorescens and P. putida , to grow and/or fluoresce on MacConkey agar at 37 C illustrates the specificity of this technique. Further studies are needed to compare the viability of P. aeruginosa on MacConkey agar to that of efficacious nonselective media.

2 types of antibody response specific for intrastrain antigenic variants of P. knowlesi can be detected in the serum of M. mulatta . One induces a change in the parasite serotype, the other is parasiticidal. The rate of synthesis of both types of antibodies to new variants increases as the host develops protective immunity and their rate of synthesis relative to one another also changes. Both these effects are possibly important in determining the level of parasitaemia.

A study of Gini's diversity function is undertaken from a geometric point of view. All values of this function that may be assumed by distributions in an n -species population are given geometric meaning with the use of four ranges. These results are used to classify the types of sets of equidiversity. A notion of higher order diversity is given and an estimate of the order which distinguishes populations with respect to diversity is derived.

The “limited” genetic variation of the cleft palate trait (CP) was increased 5 fold in the progeny of non-CP, inbred, S.C.W. Leghorn matings, when the dams’ diet was being depleted or low in riboflavin. Starting with an average incidence of 1.2 percent CP progeny, in year 1, and random mating of CP individuals, the penetrance of the trait rose in the CP line to 29.7 and 47.4 percent in years 2 and 3 respectively. The data suggested that 3 genetic factors could be related to the CP trait in the inbred line tested: 1) One or 2 loci, suggested to be recessive in nature, which are associated with the trait per se, 2) A maternal sex-limited genetic factor, and/or an imposed environmental factor associated with the level of ribolfavin deposited in the egg by the dam, which results in a threshold affecting the developing embryo and 3) A few loci, probably no more than 4, acting in an additive fashion associated with the penetrance of the trait. The possible relationships between traits showing “limited” genetic variation and teratogenic effects was briefly discussed. In addition the possibility of selecting for desirable or selecting against undesirable traits with “limited” genetic variation in selection programs was considered.

A family from Opava, Czechoslovakia, with a Gc variant is described. The variant has an electrophoretic mobility between Gc 1–1 and Gc 2–2. The notation Gc Opava (Gc Op) is proposed. The variant appears to be determined by an allele at the Gc locus, GcOp. Three family members had the phenotype Gc Op-1; three family members had the phenotype Gc Op-2.

A total of 213 Kadar from a number of villages in the Anamalai Hills, South India have been tested for 4 blood group, 5 serum protein and 15 enzyme systems, as well as haemoglobin. The frequencies of genes in the ABO, MN and Rh blood group systems are compatible with values reported previouslythe fourth blood group system Ina was invariant, all persons tested being In(a-). Similarly no variants were detected in the transferrin, caeruloplasmin and albumin serum protein systerns. The haptoglobin gene Hp1 had a frequency of 0.41, high for Indian populations and also the Gm-1–2allele had a high frequency. Two individuals had the rare phenotype Gm (–1, +2). Amongst the red cell enzyme systems distinctive variants were detected in the phospho-gluconate dehydrogenase, phosphoglucomutase (locus 1) and peptidase B systems. The allele PGDKadar controls an electrophoretically fast variant and examples of combinations of this allele with PGDA, PGDC and itself were observed. In the PGM (locus 1) system an allele controlling a slower than normal component was present and may be identical with the PGD61 (African) allele detected in a black African. Individuals homozygous for this allele and others heterozygous with it and the normal PGM11and PGM12alleles were present. A single person with a peptidase B variant was detected. The mobility of the variant band was indistinguishable from the Pep B 6 in Australian aboriginals. The pb allele of the acid phosphatase system accounted for nearly 90%, Calcutta-1 variants had a frequency of 3.3%, the AK2 gene frequency was only 3.3%, and only two cases of HbS were detected. All other systems were invariant. Theories concerning the origin of the possible negrito-like traits in a small number of Kadar were discussed and the present evidence was considered to support the possibility of past African negro admixture on a small scale. The postulated genetic reconstruction of the ancestral Kadar population suggests that they may have been similar to Melanesian and Australian aboriginal populations, but that this original genetic structure has been modified through incorporating genetic elements not only from black Africans but from surrounding Dravidian populations.

Four hexaploid spring wheats (Triticum aestivum L.), which differ only in their D genomes, were crossed in all combinations. Heterosis was expressed in F1 and F2 for number of spikes, kernel weight, and seed yield. Failure to detect significant specific combining ability among F1 progeny suggests that only additive genetic variance is involved in the inheritance of these traits. Competition between single-spaced plants was detected.

SummaryAutoradiographic localization of tritiated thymidine labeled E. coli 04 transitional phase variants in an in vitro phagocytic mixture containing polymorphonuclear leukocytes has revealed a significantly lower phagocytic index for these cell wall deficient organisms when compared to the parent bacteria from which they were derived. Although type specific antisera caused expected opsonization of the classical bacteria, there was no marked effect with the variants. The variants did not produce any detectable cytopathogenic effect on the leukocytes whereas the parent organisms were clearly toxic. The ability of such variants to resist phagocytosis may thereby provide an advantage for survival of an organism in the host and possibly lead to microbial persistence.

In an effort to study a biologically important behavioral pattern in different naturally occurring populations of the same species, the copulatory behavior ofPeromyscus polionotus from South Carolina and from Santa Rosa Island, Florida, was compared with that ofP. polionotus from the Ocala National Forest, Florida. Twelve male and 16 female South Carolina mice received 71 tests, and five male and three female Santa Rosa mice received 18 tests. The basic pattern was identical across all three samples, being characterized by no lock, no intravaginal thrusting, multiple intromissions, and multiple ejaculations. Prolonged intromissions followed organized ejaculatory series. Quantitative differences among samples were found for several measures. Intromission Frequency appears particularly susceptible to local variation. Between-population differences in copulatory behavior appear to be of a quantitative rather than a qualitative nature.