148 Darwin, and after Darwin. 



But. interesting and suggestive as this experiment 

 is in other connexions, it is clearly without sig- 

 nificance in the present one, for the reason already 

 stated. It will have to be tried on well-marked varieties 

 of other species of animals, which are known to throw 

 intermediate characters. Even, however, if it should 

 then yield a similarly negative result, the fact would 

 not tell against the inheritance of acquired characters ; 

 seeing that an ovum by the time it is ripe is a finished 

 product, and therefore not to be expected, on any 

 theory of heredity, to be influenced as to its hereditary 

 potentialities by the mere process of gestation. On 

 the other hand, if it should prove that it does admit 

 of being thus affected, so that against all reasonable 

 expectation the young animal presents any of the 

 hereditary characters of its uterine mother, the 

 fact would terminate the question of the transmission 

 of acquired characteis and this quite as effectually 

 as would a similarly positive result in the case of 

 progeny from an ingrafted ovary of a different 

 'variety. In point of fact, the only difference between 

 the two cases would be, that in the former it might 

 prove possible to close the question on the side of 

 Lamarckianism, in the latter it would certainly 

 close the question, either on this side or on the 

 opposite as the event would determine. 



The only additional fact that has hitherto been 

 published by the school of Wcismann is the result 

 of Weismann's own experiment in cutting off the 

 tails of mice through successive generations. But 

 this experiment does not bear upon any question 

 that is in debate ; for no one who is acquainted 

 with the literature of the subject would have expected 



