DEVELOPMENT 273 



continued early breeding results in decreasing the size 

 of the breed is indicated from an investigation made by 

 J. M. Jones under the writer's direction in 1912. Spe- 

 cific questions were formulated and sent to a large number 

 of successful breeders in America and Great Britain. 

 From these replies it was determined that 216 breeders 

 had observed that early mating resulted in weakening 

 the breed, diminishing the fecundity, and decreasing the 

 size. That such results followed was denied by thirty-five 

 breeders. Of the total number replying, 158 believed 

 that the size was decreased but that fecundity was not 

 diminished. It is very clear from the statistics presented 

 and from the extended replies of the intelligent breeders 

 that under certain conditions the size of the animals 

 comprising the herd of a breeder who continually breeds 

 his animals prematurely is smaller than the size of ani- 

 mals in the herds of breeders who cause their animals to 

 mate at a more mature age. 



259. Decreased size due to early breeding not in- 

 herited. In recognizing the fact that premature breeding 

 does decrease the size of the breed under certain condi- 

 tions, it is not necessary for us to assume that the tend- 

 ency to decreased size in this case is inherited. Early 

 breeding can have no direct influence in changing the 

 fundamental constitution of the germ-plasm. It cannot, 

 therefore, change the general prepotency of the breed 

 in transmitting the recognized standard qualities of the 

 race. ,We must therefore look for an explanation outside 

 of the supposed influence on the hereditary powers of the 

 breed. The real effects from premature mating are to 

 be found in the development of the individuals as affected 

 by environment. The effects of gestation and lactation, 

 if observable at* all, would be exhibited in the young par- 



