DOMESTIC ANIMALS. 



VARIATION. 



WITHOUT a tendency to variation there could be no 

 advance in organization or progress in results. 



Variation is directly opposed to heredity, so that these 

 two directly opposite forces are continually warring 

 with each other for the mastery; and it is the object of 

 the breeder to take advantage of any little change that 

 may be to the benefit of the animal which he is at- 

 tempting to improve. The improved animal does not 

 always show it in his physical proportions. Especially 

 is this true of thoroughbreds and trotters. It is impos- 

 sible to predict in advance the career of u_iy yearling 

 colt, either runner or trotter, from his form or shape, 

 and successful purchasers of horses at the breeders' 

 sales depend principally on the breeding of the animals 

 they buy, trusting that the force of heredity will be 

 stronger than the opposite force of variation. Yet we 

 very frequently find that the most carefully bred colt 

 has varied sufficiently in some particular character to 

 make him comparatively useless for racing purposes. 

 On the other hand, we occasionally find that a colt that 

 has been what may be considered rather carelessly bred, 

 will show enough variation from his parents in the 

 right direction to be an extremely valuable animal. 

 The tendency to variation is the force which is the 

 cause of those two anomalous facts. There is one 

 quality in the composition of horses and dogs that is 

 probably of more importance than any other, and is en- 

 tirely hidden in a superficial view of an animal. I refer 

 to the nervous organization. It is to this part of the 



