56 . Experimental Zoology 



there was any direct connection between the conditions in the 

 parent and in the offspring. 



On the other hand, if the results of Charrin, Delamare, and 

 Moussu are confirmed, there is a chance that diseased organs 

 at least may affect the young in utero. This would, of course, 

 only allow the inheritance of acquired characters from the 

 mother, and not from the father. This difference might give 

 us a chance to test the view that the effects are produced in the 

 embryo in utero and not in the germ-cells. It is interesting to 

 note that Brown-Sequard found that epilepsy is more often 

 transmitted through the mother than through the father. In 

 the case of mutilations, the injury may have been inflicted 

 years before, and the wounds have completely healed before 

 the young are conceived ; yet cases of this sort have often been 

 cited to show inherited effects. In such cases it is difficult to 

 see how such effects could become transmitted, especially 

 through the male. 



Weismann has given in the "Essays " referred to above an 

 interesting and very full discussion of the supposed cases of 

 inheritance of acquired characters. He himself carried out 

 some experiments with mice. For four generations the tails 

 of mice were cut off. Of the 901 mice born during this time 

 not one had a short tail, and careful measurements showed 

 that there was no shortening at all of the tail of the offspring. 

 This experiment was, it is true, almost needless, since it is cus- 

 tomary to cut off the tails of certain breeds of sheep and the 

 ears of dogs without these breeds ever having become tailless 

 or earless, and circumcision has been practiced in man for cen- 

 turies without any appreciable effect. 



Since in these cases the organs operated upon had healed 

 over before the next generation was born, there would be little 

 chance of the injury directly affecting the embryos. Moreover, 

 even if such effects are inherited, it might not follow that the 

 tails would be shortened, but at most only diseased in some 

 way. 



Recently Nussbaum has commented on this side of the ques- 



