IX 



ON THE DEVELOPMENT OF FISH EMBRYOS WITH 

 SUPPRESSED CIRCULATION ' 



1. ONE of the methods which may lead us deeper into the 

 physiology of development consists in removing one link in 

 the chain of such processes in order to see how the further 

 development, is influenced by such a step. I recently came 

 upon such an experiment, which I wish to detail in the fol- 

 lowing pages. The experiment consisted in preventing, by 

 a specific cardiac poison, the beat of the heart and the circu- 

 lation of the blood in an embryo. I had, indeed, expected 

 that under such circumstances the embryo would not die 

 immediately, but I did expect that its further development 

 would certainly be impossible. In this, however, I was mis- 

 taken. Development went on in spite of the elimination of 

 the activity of the heart ; in some cases as long as four days 

 -which was nearly half, or one-third, of the duration of the 

 embryonic stage. The consequences of the elimination of 

 the activity of the heart are also in some ways different from 

 what one might expect. The observations have not been 

 completed on all points because of the lateness of the season 

 and lack of material, but I intend to fill in these gaps next 

 season. 



The experiments were made upon a marine fish, Fundu- 

 lus, which is very common at Woods Hole. The eggs were 

 fertilized artificially in normal sea-water. In order to 

 prevent the action of the heart and the circulation in the 

 developing embryo, the eggs were put, half an hour after 

 fertilization, into sea-water to which a sufficient amount of 

 potassium chloride had been added. Potassium chloride can 



Arcliir, Vol. LIV (1893), p. .Vjr,. 



295 



