CHAPTEK V. 



ATAVISM. 



ANY peculiarity of an ancestor, more or less re- 

 mote, whether of form, color, habits, mental traits, or 

 predisposition to disease, may make its appearance in 

 the offspring without having been observed in the 

 parents. 



This form of heredity, technically termed atavism 

 (from atavus, an ancestor), is called reversion by Mr. 

 Darwin, and it has for a long time been recognized 

 by breeders, under a variety of names, as " throwing 

 back," " crying back," " breeding back," etc. 



It will, perhaps, be better to retain the term ata- 

 vism, which has been so generally in use to indicate 

 this class of cases, as it does not involve in its signifi- 

 cation any theoretical explanation of the phenomena. 



Some of the cases cited in the preceding pages, to 

 illustrate other phases of the great law of heredity, are 

 likewise examples of atavism, and we shall find also 

 in the cases quoted in this connection many illustra- 

 tions of topics discussed in other chapters. Of the 

 multitude of cases on record of this form of heredity, 

 the following will serve to illustrate its leading feat- 

 ures. Mr. Darwin states that the following case was 

 communicated to him on good authority : " A pointer- 



