218 



RAYMOND PEARL AND H. M. PARSHLEY. 



Sex of Young. 

 Time of Service. cf 9 



Early in heat 8 10 



Late in heat 4 i 



From these figures it was concluded that the theory in the 

 bald form proposed by Thury was untenable. 



The matter was again tested in Waldau and Eldena 1 with the 

 following results: 



Sex of Young. 

 Time of Service. O 71 9 



Early in heat 3 10 



Late in heat i i 



The last experimental test of the matter of which we have been 

 able to find any report (except that of Russell, loc. tit.} is that 

 of Touchon 2 who obtained the following results. 



Sex of Young. 

 Time of Service. cT 9 



Early in heat o n 



These figures are very far from extensive. In view of the 

 great practical importance of the matter, however, one would 

 have thought that they would have acted as a stimulus to more 

 adequate researches. 



It is worth while to put together all the data regarding the 

 relation of time of service to sex in cattle. We have the following 

 figures: 



These figures are suggestive. While they certainly demon- 

 strate that Thury's theory in its original form is untenable, 

 on the other hand, they strongly indicate, though they admittedly 

 do not absolutely prove, that the sex ratio in cattle may be 

 modified by controlling the time of service in relation to the 

 oestrous period. We would call attention to the fact that the 



1 Annalen ner Landwirtschaft, Wachenblatt, 1866, p. 461. 



2 Agronomische Zeitung, 1865, p. 519. 



