SEX RATIOS IN FCETAL CATTLE. 26 1 



For each 100 living born with sex ratio of IO5-5 



8th to loth month 4 stillborn, sex ratio of 130.0 



4th to 7th month 9 abortions, sex ratio of 106.3 



o to 3d month 14 abortions, sex ratio of 125.0 



Total conceptions, 127, sex ratio "X" 



Thus, for every 100 living born he concluded that there were 

 127 conceptions; 100 with a sex ratio of 105.5, and "a" still- 

 births and abortions with a sex ratio "b," in all with a primary 

 sex ratio "X." This primary sex ratio he found to be 108.47. 

 Schultz also quotes the determination arrived at by other inves- 

 tigators as follows: Bernoulli, 108.2; Gendrassiks, 108.2; 

 Lenhossek, in; Auerbach, 116.4 (who believed that it would 

 reach 125 if certain corrections could be made). Schulze thought 

 that it would not exceed no. 



It was more especially in relation to the primary sex ratio 

 and to determine whether there w r as a different viability in the 

 male and female foetuses in cattle that the present investigation 

 was undertaken and with these facts as a basis the data obtained 

 are presented. Special acknowledgment is due Dr. F. R. Lillie, 

 who suggested the problem and gave valuable assistance in the 

 interpretation of the data. 



II. DATA. 



A. Method. The work in collecting was done at one of the 

 large packing plants in Chicago during the spring of 1919. In 

 butchering the cattle at the plant, every uterus containing an 

 embryo is taken to a certain room and if the calf is large enough, 

 the skin is saved. Thus the writer was able to open the uteri 

 and record the data directly as each foetus was removed. In 

 this way any errors or neglect in birth registration are avoided. 



The data embraces 1,000 individuals and the sex and length, 

 as an indication of age, were recorded. Observations were also 

 made on the number of corpora lutea in every case where this 

 was possible, especially when twins were found, in which case 

 the position in the uterus also was noted. The complete tabular 

 list with the crown-rump measurement and sex of each individual 

 as removed from the uterus is omitted in this article. 



B. Items of General Importance. -In regard to the number of 

 corpora lutea, in all of the ovaries examined, about 300 in all, 



