78 ARTIFICIAL PARTHENOGENESIS AND FERTILIZATION 
ESE OS Se Le re 
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.! 
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.” 
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 Ckloral 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. 
2 Loeb, op. cit. 
