180 TRANSMISSION OF ACQUIRED CHARACTERS 



the hardening of the ancestral horses' hoofs as they left the 

 marshes and ran on harder ground ; they picture the giraffe by 

 persistent effort lengthening out its neck a few millimetres every 

 century, as the acacia raised its leaves higher and higher off 

 the ground ; and they say that animate nature is so full of 

 evidences of the inheritance of acquired characters that no 

 further argument is needed. 



But all this is a begging of the question. It is easy to find 

 structural features which may be interpreted as entailed acquired 

 characters, if acquired characters can be entailed. Obviously, 

 however, we must deal with what we can prove to be modifi- 

 cations, or with what we can plausibly regard as modifications 

 because we find their analogues in actual process of being 

 effected to-day. 



It is easy to say that the blackness of the negro's skin was 

 produced by the tropical sun, and that it is now part of his 

 natural inheritance. It is easy to say this, but absolutely 

 futile. Let us first catch our modifications. 



The Golden Rod (Solid ago virgaurea) growing on the Alps is 

 precocious in its flowering when compared with representatives 

 of the same species growing in the lowlands. Hoffmann found 

 that Alpine forms transplanted to Giessen remained precocious, 

 therefore the acquired precocity had become heritable. But 

 there is no evidence that the precocity was acquired ; it may 

 have been the outcome of the selection of germinal variations. 



The African Wart-hog (P ha co cheer us) has the peculiar habit 

 of kneeling down on its fore-limbs as it routs with its huge tusks 

 in the ground and pushes itself forward with its hind-limbs. 

 It has strong horny callosities protecting the surfaces on which 

 it kneels, and these are seen even in the embryos. This seems 

 to some naturalists to be a satisfactory proof of the inheritance 

 of an acquired character. It is to others simply an instance 

 of an adaptive peculiarity of germinal origin wrought out by 

 natural selection. 



