INHERITANCE OF ACQUIRED CHARACTERS 89 



^ Sumner kept mice in a constant but abnormally 

 high temperature of 26 C. with the result that the 

 ears, tail, and feet grew noticeably larger than in 

 control animals kept in ordinary lower temperatures, 

 while at the same time the general hairiness of the 

 body decreased. It should be remembered, however, 

 that mice are mammals which pass through an ex- 

 tended uterine existence, so that it is easy to see how 

 the offspring in this case were subjected to the same 

 excessive temperature as the parents for a period 

 sufficient to amply account for their subsequent 

 variation when removed to a normal environ- 

 ment. 



>- Lederbaur finds that the wayside weed Capsella, 

 which in the course of many years has gradually 

 crept along ,the roadside up into an Alpine habitat 

 and there "acquired" Alpine characters, upon being 

 transplanted to the lowlands retains its Alpine 

 modifications. Although this case has been cited 

 as an authentic instance of the inheritance of ac- 

 quired characters, is it not possible that the conquest 

 of the Alps by Capsella has been due, in the course 

 of time, not to the inheritance of acquired characters 

 at all, but to a gradual natural selection of just those 

 germinal variations which best fitted it to cope with 

 Alpine conditions until, finally, a strain of germplasm 

 producing somatoplasm suitable to Alpine conditions 

 has been isolated in the form of an elementary species 

 derived from the original type ? If this is what has 

 happened, of course such germplasm would give 

 rise to Alpine plants whether individual plants grew 



