animals of the world. How that problem was an- 

 swered, I will show. But what should also become 

 obvious is that in the showing, the answer to an- 

 other equally pretty problem is presented. I have 

 already given more than a hint that the internal 

 conditions of the embryo's development are in- 

 herent and inherited. But development is also 

 conditioned by external environment. In fact, 

 every living thing throughout the entire period of 

 its life reacts to its environment by certain changes 

 in its physiological functions or its form. The 

 embryo, like the adult, is an active balanced prod- 

 uct, a product of the response of the inherited or- 

 ganization to the external conditions influencing 

 its development. Therefore, it is patent that this 

 development can be altered if the conditions are 

 changed. 



This I strove to do by raising some of my 

 embryos in artificial sea-water containing no lime- 

 salts. The change to this deficient medium proved 

 to be too much for the majority of them; however, 

 a few hardy ones survived, and these I nursed 

 along with rare and keen solicitude. My consid- 

 erate care was amply rewarded. For behold the 

 result! the later larvae failed to grow not only their 



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