280 Studies in the Theory of Descent. 



appears suddenly in the ontogeny ; whereas, on 

 the other hand, it appears certain that new, or 

 more advanced, but simpler characters, predo- 

 minate in the last stage of development. We are 

 thus led to the following modification of the fore- 

 going conclusion : Newly acquired characters 

 undergo, as a whole, backward transference, by 

 which means they are to a certain extent dis- 

 placed from the final ontogenetic stage by charac- 

 ters which appear later. 



This must be a purely mechanical process, de- 

 pending on that innate law of growth, the action 

 of which we may observe without being able to 

 explain fully. Under certain conditions the ope- 

 ration of this law may be prevented by natural 

 selection. Thus, fpr instance, if the young cater- 

 pillars of Anceryx Pinastri have not acquired the 

 characteristic marking of the adults, it is probably 

 because they are better protected by their re- 

 semblance to the green pine-needles than they 

 would be if they possessed the pattern of the 

 larger caterpillars in their last stage. 



The backward transference of newly acquired 

 characters may also possibly be accelerated when 

 these characters are advantageous to the younger 

 stages ; but this transference takes place quite 

 independently of any advantage if the characters 

 are of indifferent value, being then entirely brought 

 about by innate laws of growth. 



That new characters actually predominate in 



