The Decisive Experiment 171 



ence of the limb or other part of the body which was 

 destroyed in the parent. 



In order to make this more apparent let us con- 

 sider some one of the numerous rats from which 

 Weismann cut off the tails, and which that author has 

 rightly brought forward as proving that the surgical 

 operation of amputation is not inherited. Let us sup- 

 pose that in the young rat when once his development 

 was completed and he had arrived at about the age at 

 which the old rat had undergone the amputation, really 

 showed at the spot at which the amputation took place 

 a tendency to reproduce the same phenomena of cicatri- * 

 zation and reestablishment of the new local equilibrium 

 which had supervened in the parent. It is evident that 

 the absence of the tail is a necessary condition in order 

 to make the reproduction of these phenomena materially 

 possible. This tendency must then be hindered and per- 

 haps absolutely suppressed so long as the tail remains a 

 part of the organism. 



It is interesting in this connection to note that Kohl- 

 wey has obtained in one and the same individual a com- 

 pletely negative result in respect to the inheritance of 

 mutilations, but a positive result in respect to the trans- 

 mission of habit : He cut off the posterior digit from 

 the feet of some pigeons which thereupon turned back 

 another digit in order to retain their perch; and in one 

 instance this habit was reproduced. 136 



The decisive experiment upon the inheritance of ac- 

 quired characters must leave amputations and similar 

 sudden variations out of consideration, since either their 

 effect is to bring about the reestablishment of an exclu- 



16 H. Kohlwey: Arten und Rassenbildung. Eine Einfuhrung in 

 das Gebiet der Tierzucht. Leipzig, Engelmann, 1897, P. 67. 



