78 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 



the first two vessels had all formed nuclear spindles at the right 

 time, and began to disintegrate after four or five hours. After 

 ten hours none of these eggs could be induced to develop by 

 treatment with hypertonic sea-water. On the other hand, the 

 eggs which had been in the current of hydrogen had formed no 

 spindle and were perfectly intact when disconnected from it. 

 They could still be induced to develop by treatment with hyper- 

 tonic sea-water. Even after remaining twenty-four hours in 

 the stream of hydrogen the eggs maintained their shape intact. 

 Just the same sort of results were obtained upon the addition of 

 a little KCN to the sea-water, by which means the development 

 was arrested. By stopping development (as a result of inhibit- 

 ing oxidations) the eggs are kept from that disintegration after 

 membrane formation to which they would be condemned at 

 room temperature. Hence we must come to the conclusion 

 that membrane formation does indeed initiate development, 

 but that it leaves the egg in a condition in which the cell divi- 

 sion becomes fatal to it. If we prevent cell division the egg 

 survives. 1 



This conclusion is supported by the observation that if the 

 development of the eggs after artificial membrane formation be 

 stopped for several hours, they are then able to develop even at 

 room temperature, and not only to blastulae but also to plutei. 2 

 I first became aware of this fact when I put eggs after mem- 

 brane formation (with butyric acid) into sea-water from which 

 the air had been displaced by a current of hydrogen. At 

 various intervals eggs were replaced in normal sea-water from 

 that lacking oxygen. It turned out that eggs which at 15 C. 

 had been less than three hours in the sea-water that lacked 

 oxygen all disintegrated after the return to normal sea-water; 

 but that of the eggs which had been three hours or a little longer 



1 Chloral hydrate acts in the same way, although it does not diminish the rate 

 of oxidation; but it inhibits the developmental process and cell division and thus 

 prevents the fatal disintegration of the egg. 



Loeb, op. cit. 



