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Statistical analysis of the trapnest records of turkeys extending over seven years shows that date of first egg is a better measure of sexual maturity in turkeys than age at first egg. Date of first egg is little influenced by variation in the time of hatch within the normal hatching season of almost two months, whereas age at first egg is influenced, the later-hatched birds starting to lay when younger than the earlier-hatched birds. Moreover, genetic differences in sexual maturity can more readily be demonstrated with date of first egg than with age at first egg. Selection for early and late sexual maturity was effective in establishing lines that differed significantly in date of first egg. When these lines were crossed the results differed according to which way the cross was made. The progeny of late male x early female laid earlier than the birds in the late-maturing line but later than the progeny of the reciprocal cross. In at least one case, the progeny of the latter (early male x late female) la...

Observations were made on 19,446 turkey embryos and poults, of which 50.17 per cent. were males. The sex ratio of hatched poults was 49.20 per cent. males, due to heavier mortality among male embryos. The sex ratio of 8,548 chicken embryos and chicks was 49.54 per cent. males. When combined with comparable published data, the sex ratio obtained was 49.19 per cent. males or 0.98 ± 0.38 per cent. lower than for turkeys. During the last week of incubation more male than female turkeys died, whereas the reverse was true for chickens. There was a larger number of males than females in small samples of embryos of both species that died between the time when sex could be readily identified and the last week of incubation, but the significance of this finding can not be established in absence of further data. It is suggested that sex-linked genes have little or no influence on the sex ratio of the strains of turkeys studied here, whereas they perhaps exert an influence on the secondary sex ratio of at least some ...