30 CALIFORNIA ACADEMY OF SCIENCES. 



in favor of or against the supposition that modifications 

 of the body-cells are transmitted to the germ-cells. 

 Now these modifications must clearly be of such a nature 

 as to be receivable by the cells without in any way de- 

 stroying their integrity. The destruction or removal of 

 cells is something very different from this. If it were 

 proved that mutilations are inherited, this would not 

 necessarily show that normal cell-modifications are trans- 

 missible. And if the evidence in favor of inherited 

 mutilations breaks down, as I believe it does, this does 

 not show that more normal modifications such as those 

 with which we are familiar, as occurring in the course 

 of individual life, are not capable of transmission." 



Weismanii has devoted some attention to the reported 

 cases of the inheritence of mutilations, and has reached 

 the conclusion that all the published instances are either 

 untrustworthy or of such a character that they do not 

 conclusively prove that a case of mutilation has ever 

 been inherited. 



In commenting upon his explanation of reputed cases 

 of the transmission of rudimentary tails, he says:* " We 

 have seen that the rudimentary tails of cats and dogs, 

 as far as they can be submitted to scientific investiga- 

 tion, do not depend upon the transmission of artificial 

 mutilation, but upon the spontaneous appearance of de- 

 generation in the vertebral column of the tail. The 

 opinion may, however, be still held that the customary 

 artificial mutilation of the tail, in many races of dogs 

 and cats, has at least produced a number of rudimentary 

 tails, although, perhaps, not all of them. It might be 

 maintained that the fact of the spontaneous appearance 

 of rudimentary tails does not disprove the supposition 

 that the character may also depend upon the transmis- 

 sion of artificial mutilation. 



* Essays on Heredity, 1891, I, p. 443. 



