5] 



IN ONTOGENESIS 



823 



Some curious experiments which may have a relation to these 

 facts were made by Remotti, who caused the eggs of Salmo lacustris 

 to develop, some in darkness, some in the illumination of a very 

 powerful electric light. At the end of development the serum of the 

 embryos which had developed in the light reacted more slowly and 

 feebly with quinol than that from those which had developed in the 



Typical curves 



Remobbi 



T038 



I I I I M M I I I I I I I I I I I I I I I 1 M i I I I 11 M I I I 



Days of development 



Fig. 200. Each curve begins at fertilisation. 



dark. By the continuation of similar experiments Remotti hoped 

 to identify in some way the factors responsible for the effect of light 

 on developing embryos. For further discussion of this subject see 

 Section 2-17. 



Various other attempts have been made to unravel the mechanism 

 responsible for ontogenetic vertical migrations. Sanzo reported, 

 though without giving any figures, that the perivitelline liquid of 

 murenoid eggs has a lower freezing-point at the end of development 

 than at the beginning, i.e. that probably the membrane becomes 



