300 PRINCIPLES OF STOCK-BREEDING. 



vant, the Ayrshires, during nine and a half years, pro- 

 duced "54 bull-calves and 43 cow-calves a propor- 

 tion of 125.5 males to 100 females ; " while the Ayr- 

 shires of the Oneida Community produced " 26 bull 

 and 31 heifer calves a proportion of 83.8 male to 

 100 female births." * 



Although the last-mentioned cases have no direct 

 bearing upon the theory in question the period of 

 heat at which copulation took place not being stated 

 they are of interest in this connection, as they fairly 

 represent the variations that take place without ap- 

 parent cause, under ordinary methods of management. 



In the following cases of late impregnation, re- 

 ported by Mr. Slade, the males are in excess, as they 

 were also in some of the instances of early impreg- 

 nation above mentioned. " Three years ago last 

 spring," says Mr. Slade, " I had a very likely sow that 

 was in heat, and I let her remain thirty-six hours be- 

 fore taking her to the boar. The result was she had 

 seventeen pigs ; eleven of them were males and the 

 others females. ... At the next litter she remained 

 about the same length of time in heat before taking 

 the boar, and had nine male and two female pigs." * 



On many farms the males run with the breeding 

 females during the season, so that copulation takes 

 place at the beginning of the period of heat ; and yet 

 in such cases there is nearly an equal number of each 

 sex on the average, taking a number of years together, 

 while the males may be in excess one year and the 

 females in excess another year. 



1 Scientific Farmer, 1876, p. 166. 



3 "Massachusetts Agricultural Report," 1866-'67, p. 117. 



