PRESERVATION OF THE LIFE OF THE EGG 285 
‘which are placed for ten or fifteen minutes in 100 c.c. of sea- 
water+4c.c. N/10 HCl, without coming into contact with 
alkaline sea-water, ripen much more slowly, generally not at 
all, when after that time they are replaced in normal sea-water. 
They retain also, as long as they are unripe, the full normal 
appearance of living eggs, until they eventually fall victims 
to bacteria. Unripe eggs too, when placed in neutral sea-water, 
do not ripen for the most part, and retain their normal appear- 
ance if they remain immature. 
It appears to follow from this experiment that the same 
process which lies at the bottom of the maturation of the star- 
fish egg also leads to its death, unless it is prevented by those 
measures which we designate as fertilization. I now tried 
whether it is possible to keep the ripe eggs alive longer through 
lack of oxygen. In fact I obtained some positive results in 
this connection. Starfish eggs were spread out in a thin layer: 
After three hours 75 per cent of the eggs had ripened. A 
part of the ripe eggs was immediately placed in narrow 
glass tubes, in which the deeper layers suffer the same lack 
of oxygen. A second portion was placed in small flasks, 
through which was led a constant stream of pure oxygen. 
Next morning, fifteen hours after the eggs were placed in the 
oxygen, the different portions of eggs were tested. Those eggs 
placed in the current of oxygen showed in one dish 98 per cent 
of ripe, dark, and dead eggs, and 2 per cent of unripe, living 
eggs. The eggs remaining in normal sea-water contained as 
before some 78 per cent of ripe eggs, which, however, were all 
black and dead, with the exception of a few which had begun to 
divide and were alive. The unripe eggs were also living. On 
the other hand, those eggs which had been in the glass tubes, in 
complete, or relatively complete, lack of oxygen, were nearly 
all alive. This observation, in fact, indicates that the same 
process which leads to the maturation of the egg also causes the 
death of the egg unless it is prevented in time. In this way 
