166 EVOLUTION AND ANIMAL LIFE 



the union of the two parental germ cells, "the gate of gifts is 

 closed." No trait or quality can ever be acquired of which at 

 least the elements are not involved in the original inheritance. 



"What is transmitted to the infant," observes Dr. Archdall 

 Reid, "is not the modification [of the parent], but only the 

 power of acquiring it under similar circumstances. The power 

 to acquire fit modifications in response to appropriate stimula- 

 tion is that vv^hich especially differentiates high animal organ- 

 isms from low animal organisms." 



Atavism or reversion is the process of "throwing back," by 

 which in some degree an individual resembles a distant ancestor. 

 Under the name of "atavism," according to Yves Delage, are 

 included three very different things: 



(a) The transmission in one family of indi\ddual characters, 

 which, latent for several generations, suddenly reappear. This 

 is family atavism, and its nature is readily recognized. 



(b) The reappearance, more or less regularly in a race, of 

 characters of an allied race, from which the first race may have 

 been derived. This is race atavism. Of this nature are the 

 zebra stripes sometimes seen in mules. 



(c) The appearance of characters abnormal for the race in 

 which they appear, but which are normal in other races sup- 

 posed to be ancestral. This is atavism of teratology. An illus- 

 tration is the occasional appearance in the modern horse of rudi- 

 ments of additional toes, with partly developed hoofs. 



"Everything is possible in heredity," observes Delage. 

 "One may always find examples of election, of blending (of 

 mosaic), of combination, of resemblance direct, and of resem- 

 blance reversed. To give to these groupings the name of laws 

 would be an abuse of language, since not one of these rules is 

 exclusively true. In reality there is no law of resemblance be- 

 tween a child and its parents. All is possible, from a difference 

 so great that there is not a trait in common, to an almost perfect 

 identity with one or the other parent, with every intermediate 

 degree of blending of characters and combination of resem- 

 blances." 



The name " telegony " is given to the supposed influence of 

 the first male on the future offspring of the female. This theory 

 of telegony rests mainly on a case of a mare which was first im- 

 pregnated by a quagga, and whose subsequent colts from males 

 of her own species had quagga-like markings. The supposed 



