398 STUDIES IN GENERAL PHYSIOLOGY 



In order to be able to compare these results with those 

 obtained on the Ctenolabrus egg, I repeated the experiments 

 on Funduhis, using the same method of replacing oxygen 

 by hydrogen, and the same apparatus which had been used 

 in the case of the Ctenolabrus egg. 



The results obtained were in entire harmony with our 

 earlier findings. When freshly fertilized eggs of Fundulus 

 are introduced into the Engelmann chamber, and a vigorous 

 stream of hydrogen is passed through it, the eggs divide not 

 only once, but continue to do so for fifteen to twenty hours, 

 until a blastoderm is formed which extends over the sur- 

 face of the egg. The result was the same when the eggs 

 were put in an Engelmann chamber and kept for two and 

 one-half or three hours on ice, during which time they were 

 exposed to a vigorous stream of hydrogen. When the eggs 

 were then exposed to room temperature, segmentation at once 

 began and continued in a regular manner. During the 

 entire course of the experiment hydrogen was permitted to 

 pass through the chamber. 



As long as the number of the cleavage-cells was so small 

 that they could be counted, it could be seen that develop- 

 ment without oxygen occurred as rapidly as in oxygen. 

 Whether this holds also for later stages when cleavage 

 approaches the standstill cannot be determined, as the cells 

 are then too small to allow one to count them. Not only 

 cleavage, but also growth, of the blastoderm, that is to say, 

 increase in area (at the expense of the yolk (?), 1903) occurs 

 in the absence of oxygen. The blastoderm grows from a 

 small area to a large area on the surface of the yolk. 



If Fundulus eggs are allowed to remain more than twelve 

 to fifteen hours in hydrogen, the cells nevertheless do not 

 liquefy, as is the case in Ctenolabrus in the absence of 

 oxygen. Even after twenty-four hours no such phenomena 

 are observable in the Fundulus egg. I have shown in 



