THE SUPPOSED TRANSMISSION OF MUTILATIONS. 425 



For this reason, the defenders of the Lamarckian principle, who 

 have come forward in rather large numbers recently 1 , have en- 

 deavoured to show that these observations are conclusive, and there- 

 fore of the highest importance. For the same reason I believe that 

 it is my duty, as I take the opposite view, to explain what I think 

 of the value of these apparent proofs of transmitted mutilations. 



It can hardly be doubted that mutilations are acquired characters : 

 they do not arise from any tendency contained in the germ, but 

 are merely the reaction of the body under external influences. They 

 are, as I have recently expressed it, purely somatogenic characters 2 , 

 viz. characters which emanate from the body (soma) only, as op- 

 posed to the germ-cells ; they are therefore characters which do 

 not arise from the germ itself. 



If mutilations must necessarily be transmitted, or even if they 

 might occasionally be transmitted, a powerful support would be 

 given to the Lamarckian principle, and the transmission of functional 

 hypertrophy or atrophy would thus become highly probable. For 

 this reason it is absolutely necessary that we should try to come to 

 a definite conclusion as to whether mutilations can or cannot be 

 transmitted. 



We will now consider in greater detail the facts which have 

 hitherto been brought forward upon this point. It is not my 

 purpose to discuss every single case which has been mentioned 

 anywhere or by anybody ; such a discussion would hardly lead 

 to any result. I propose to select a small number of such instances, 

 in order to show why they cannot be maintained as proofs. I 

 shall chiefly deal with cases which have been brought forward as 



[ l One of the rnost remarkable forms of this revival of Lamarckism is the establish- 

 ment in America of a ' Neo-Lamarckian School,' which includes among its members 

 many of the most distinguished American biologists. One of the arguments upon 

 which the founders of the school have chiefly relied is derived from the comparative 

 morphology of mammalian teeth. The evolution of the various types are believed 

 to be due to modifications in shape, produced by the action of mechanical forces 

 (pressure and friction) during the life of the individual. The accumulation of such 

 modifications by means of heredity explains the forms of existing teeth. 



It may be reasonably objected that the most elementary facts concerning the de- 

 velopment of teeth prove that their shapes cannot be altered during the lifetime of 

 the individual, except by being worn away. The shape is predetermined before the 

 tooth has cut the gum. Hence the Neo-Lamarckian School assumes, not the trans- 

 mission of acquired characters, but the transmission of characters which the parent 

 is unable to acquire ! E. B. P.] 



2 See p. 412 of the preceding Essay (VII). 



