DEVELOPMENT OF THE EMBRYO. 25 



examination we may obtain by day a view of almost 

 all the stages, with the exception of those occurring on 

 the first night. And of this the reason is, that when 

 the weather is not cold, the development is almost as 

 far- advanced at the conclusion of the first day as in 

 cold weather at the conclusion of the second night. 

 It is, however, always advisable, with a view of 

 obtaining a continuous idea of the development, to 

 follow the embryos obtained from one spawning for 

 thirty-six hours from the gastrula stage. 



In order to be thoroughly acquainted with the fully 

 normal activitv of all the stages. I have also studied 



y 



embryos of every degree of development fished out of 

 Pantano. 



After the perforation of the mouth and first gill-slit, 

 I was able to keep the larvae a yet longer time alive 

 in the glasses. The development of the latter is, as 

 might be expected, poor as compared with those 

 which are reared in Pantano. 



I preferred, therefore, to examine the organization 

 of the larvae and their further development in 

 individual specimens fished in the sea. 



