272 THE BREEDING OF ANIMALS 



a retardation of the growth of the young parents and, in 

 some cases, a permanent dwarfing of the mother. 



The supposed evil results following premature preg- 

 nancy must result either from variations produced in the 

 fundamental constitution of the germ-plasm or in changes 

 in the soma- or body-cells. Those breeders who contend 

 that long-continued breeding of immature animals results 

 in actually decreasing the size of the race or breed believe 

 that the real character of the breed has been changed, and 

 changed in such a way that the individuals of the breed 

 are no longer able to produce offspring which possess the 

 capacity to develop into animals of the recognized stand- 

 ard size of the breed. They would insist that the funda- 

 mental nature of the breed has been changed in such a 

 way as permanently to affect their hereditary character. 

 It is obvious that if this contention of breeders is correct, 

 it is contrary to our present ideas of the inheritance of 

 acquired characters. Biologists generally would first 

 insist on a more accurate demonstration of the alleged 

 fact that the size of the breed is actually diminished as a 

 result of early pregnancy and lactation. If it should 

 be found that this practice has apparently resulted in a 

 smaller breed, the biologist would undertake to explain 

 the observed fact on different grounds. 



258. Premature breeding decreases size. First, is it 

 true that premature breeding has ever resulted in decreas- 

 ing the size of the breed ? It must be admitted that 

 experienced breeders are very often accurate observers. 

 Investigators who disregard the facts which have been 

 determined by practical breeders through a long period 

 of successful experience are neglecting a valuable source 

 of knowledge on many of the complex problems of heredity 

 and development. That breeders have observed that long- 



