Apr. 15,1924 Relation of Antecedent Egg Production to Sex Ratio 
201 
of incubation and on most of which the sex was determined. During the norma 
hatching season the chicks which hatched were banded, and a note was made 
of the sex, which was later checked by observation of the secondary sexual 
characters. Up to and including the time of the normal hatching season, the 
chicks were allowed to hatch, and whatever chicks hatched were killed and 
dissected immediately. Subsequent to the hatching season the eggs was 
removed from the incubator about the nineteenth day and were all dissected. 
Occasionally an egg would become lost, usually through being broken in attend¬ 
ing the incubator and no record being made. The sex on a few chicks was 
undetermined, either through two or more chicks getting together in the hatch¬ 
ing trays or through chicks becoming lost during the growing season. Although, 
under normal conditions, the sources of loss of records among growing chicks 
are numerous, including loss from enemies of the poultry flock and loss of leg- 
band before the insertion of the permanent wing band, the number of eggs and 
chicks in this experiment on which no records were obtained was small indeed 
Furthermore, it is probably true that all cracked and missing eggs and all missing 
chicks would constitute a random sample of the entire population as far as the 
matter of sex ratio is concerned. 
The weights of the eggs are considered in relation to production and to sex 
ratio. Using another group of birds, the weights of the yolks of all eggs laid 
during the first year of production have been determined and are considered 
in relation to production and to sex ratio. The water content of a number of 
eggs laid at different periods of production has been determined, and this also is 
considered in relation to production and to sex ratio. 
RESULTS 
Before undertaking the presentation of the results from this experimental 
study, it is desirable to call attention to one or two matters. The sex ratio is 
presented in terms of the percentage of the males in the total population. In 
subsequent sections of this paper the sex ratio will be given in terms of the male 
ratio and will de designated as R <$. 
In the context which follows the following symbols have the attached signifi¬ 
cance: Rd'H=per cent of males in all chicks which hatched; R<?D=per cent 
of males among all dead embryos in which sex was determined. 
Table I .—Summary table showing complete results of the three-year period 
1919-22 
Year 
Num¬ 
ber of 
birds 
Total 
egg pro¬ 
duc¬ 
tion 
Cracked 
eggs 
Infer¬ 
tile 
eggs 
Dead 
em¬ 
bryos 
not 
sexed 
Missing 
eggs 
and 
chicks 
Total 
fe¬ 
males 
Total 
males 
Total 
sexed 
Sex 
ratio 
1919-20_ 
18 
1,845 
116 
132 
564 
7 
550 
476 
1,026 
46.39±0.64 
1920-21.. 
8 
979 
57 
217 
199 
5 
246 
255 
501 
50.89±0.85 
1921-22_ 
19 
1,779 
82 
551 
251 
26 
440 
429 
869 
49.37-b0.66 
Total_ 
45 
4,603 
255 
900 
1,014 
38 
1,236 
1,160 
2,396 
48.41=fc0.47 
Percent.— 
5.54 
19.55 
22.03 
0.82 
26.85 
25.20 
52.05 
Table I gives the mean sex ratio of the experimental fowls for the whole three 
years. It will be noticed that the sex ratio for the second year is higher than for 
either of the other two years, but it should be explained that during the second 
year two of the eight birds gave very high male ratios throughout the year. 
The question which arises is whether the sex ratio of 48.41 ±0.47 represents 
the normal sex ratio for the domestic fowl, since this ratio is determined upon 
the total production for the first year, whereas most of the sex ratios presented in 
biological literature deal with ratios determined during the normal hatching sea¬ 
son only. 
