358 APPENDIX 



of securing, at one step, great advancement. The -first 

 type is that on which Darwin * based his theory of the 

 origin of species; the second was developed by De Vries.t 

 thus forming two schools of thought which have not yet 

 become thoroughly reconciled. It is probably by muta- 

 tion that we may explain the first occurrence of crests in 

 pigeons, feathers on the legs of fowls and long hair in 

 guinea-pigs. Proper mating and selection fixed these sud- 

 den abnormalities ; variation of the continuous type, guided 

 by the breeder's skill, caused their gradual improvement. 



Breeders often have maintained the potency of one sex 

 over the other; that is, that the characters of the male domi- 

 nate those of the female, or mce versa. There is also much 

 talk of the effect of the age of the parents in governing 

 inheritance in the offspring. There is no evidence to sup- 

 port either of these theories, but the prepotency of indi- 

 viduals, regardless of age or sex, is undoubted. Certain 

 specimens, which may be discovered only by actual experi- 

 ment, are found to transmit given characters with great 

 regularity, and not infrequently pass on the prepotent quality 

 as well. The tendency may be either toward or away from 

 the ideal of the breed. In the former case advance may be 

 made in a comparatively short time, which could be accom- 

 plished by the usual slow steps only after years of pains- 

 taking selection. 



We have seen that selection is the governing rod which 

 controls the tendency of heredity. We must go one step 

 further, however, and realize the truth that selection within 

 well-established family lines is the surest way to success. 

 Once well developed, there appears to be a tendency for in- 

 heritance to follow certain paths, and any crossing outside 

 of the family has something of the same effect as crossing 



* Darwin, Charles : The Origin of Species. 



t De Vries, Hugo : Species and Varieties, Their Origin by Mutation. 



