448 SUPPOSED TRANSMISSION OF MUTILATIONS. [VIII. 



The supposition of the accumulative effect of mutilation is en- 

 tirely visionary, and cannot be supported except by the fact 

 that accumulative transformations of the germ-plasm occur; 

 but of course this fact does not impl}'^ that mutilations belong 

 to those influences which are capable of changing the germ- 

 plasm. All the ascertained facts point to the conclusion that 

 they have not this effect. The transmission is all the more 

 improbable because of the striking form of the mutilation in all 

 cases which are relied upon as evidence. The only objection 

 which can be raised is to suppose that the absence of the tail 

 is less easily transmitted than other mutilations, or that mice 

 possess smaller hereditary powers than other animals. But 

 there is not the slightest evidence in favour of either of these 

 suggestions ; the supporters of the Lamarckian principle have, 

 on the contrary, always pointed to the transmission of mutilated 

 tails as one of their principal lines of evidence. 



The opinion has often been expressed that such transmission 

 need not occur in everj^ case, but may happen now and then 

 under quite exceptional conditions with which we are unac- 

 quainted : for this reason it might be urged that all negative 

 experiments and every refutation of the ' proofs ' of the trans- 

 mission of mutilations are not conclusive. Only recently, a 

 clever young zoologist said in reference to Kant's statements 

 upon the subject, that perhaps the most decided opponent of 

 the transmission of mutilations would not venture nowadaj^s to 

 maintain his view with such certainty, ' for it must be admitted 

 that the transmission of acquired characters may take place 

 at any rate as a rare exception.' Similar opinions are often 

 expressed, especially in conversation, and yet they can mean 

 nothing except that the transmission of acquired characters has 

 been proved ; for if such transmission can take place at all, it 

 exists, and it does not make the least difference theoretically 

 whether it occurs in rare cases or more frequently. Some- 

 times heredity has been called capricious, and in a certain 

 sense this is true. Heredity appears to be capricious because 

 we cannot penetrate into its depths : we cannot predict whether 

 any peculiar character in the father will reappear in the child, 

 and still less whether it will reappear in the first, second, or 

 one of the later children : we cannot predict whether a child 

 will possess the nose of his father or mother or one of the 



