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THE AMERICAN NATURALIST [Vol. XL VI 



same direction. (7) There is a predisposition to similar 

 progressive variations in descendants of one stock 

 (termed " analogous or parallel variation") due to un- 

 known causes acting on similarly constituted organisms. 8 

 (8) There is a marked prepotency in heredity in saltatory 

 types, e. g., ancon sheep, turnspit dogs. (9) There is ' 4 in 

 a certain sense" a mosaic inheritance (after Naudin) 

 observed in hybrids, or character segregation by self at- 

 traction and self affinity. Similarly there is an exclusive 

 inheritance, as observed in characters derived exclusively 

 from the father or mother and lying dormant or latent 

 for many generations. (10) There is a particulate inher- 

 itance, for example, of the special quality of vigor and 

 endurance observed in descendants of the racehorse 

 "Eclipse"; i. e., a dominance of single characteristics. 



(11) A large number of individual variations cited are 

 antithetic characters rather than slight or infinitesimal 

 gradations of similar characters, e. g., 



Erect ears Drooping ears 



Fertility Sterility 



Immunity . Non-immunity 



Resistance to environment Non-resistance to environment 



(12) Environment directly affects the antithetic charac- 

 ters of sterility and fecundity. (13) New characters may 

 appear and old ones disappear at any stage of develop- 

 ment. 9 (14) There is a similar age heredity or inher- 

 itance at corresponding periods of life. (15) There is a 

 sex-limited heredity. (16) There is a correlated varia- 

 bility or coupling of new characters in heredity, e. g., 

 black color of the skin and immunity from disease. (17) 

 Particulate inheritance as shown in non-blending colors, 

 6. g., gray and white mice produce piebald young, or gray 

 or white young, but never a blend between gray and 

 white. (18) Old characters lying latent are ready to be 

 evolved under certain old environmental conditions. 

 Thus we observe the ontogenic revival of feral characters 



8 Vol. II, p. 329. 

 'Vol. Et, p. 392. 



