182 BLIND VERTEBRATES AND THEIR EYES. 



by which individually acquired characteristics are enabled to appear in the next 

 generation. The facts, which are patent, have been formulated by Hyatt in his 

 law of tachygenesis. Histogenic development is a prolonged process, and onto- 

 gcnetic degeneration is still operative, at least, in Amblyopsis. 



Degeneration is not the result of the ingrowth of connective tissue cells as far 

 as I can determine. It is rather a process of starving, of shriveling, or resorption 

 of parts. 



From the foregoing it is evident that degeneration has not proceeded in the 

 reverse order of development, rather the older normal stages of ontogenetic develop- 

 ment have been modified into the more recent phyletic stages through which the 

 eye has passed. The adult degenerate eye is not an arrested ontogenetic stage of 

 development, but a new adaptation, and there is an attempt, in later ontogeny at 

 least, to reach the degenerate adult condition in the most direct way possible. 



