NaturaL DEATH AND FERTILIZATION 731 
recognized. The sterilized flasks which were opened were 
at all times free from foul odor, while the unsterilized flasks 
gave off a penetrating stench, often after one, invariably 
after two, days. The microscopic examination of the sea- 
water for bacteria was always negative in the sterilized flasks, 
always positive in the other flasks. In those flasks to which 
2c.c. of the putrid culture of starfish eggs had been added, 
bacteria and infusoria were exceedingly numerous from the 
beginning. 
Six hours after the beginning of the experiment one flask 
of each of the three series was opened, and the eggs 
examined microscopically. The picture was the same in all 
three flasks. Nearly all the eggs were mature, and a small 
number of them were opaque or black. But what is of the 
greatest importance to us is the fact that the percentage of 
opaque dead eggs was just as great in the sterile culture (if 
not greater) than in the unsterilized or the infected sea- 
water. 
Twelve hours later, that is to say eighteen hours after the 
beginning of the experiment, one of the flasks of each of the 
three cultures was again opened. At this time nearly all the 
eggs of the sterile culture were opaque or black, and a few 
were already granular. In the two other cultures an equal 
percentage of the eggs were opaque. The eggs, therefore, 
die just as rapidly in the sterilized flasks which are abso- 
lutely free from bacteria as in the flasks containing bacteria. 
Death follows from internal causes, and so rapidly that the 
few bacteria in the sea-water are scarcely able to accelerate 
the death of the eggs. The eggs have already died from 
internal causes before the bacteria can attack them in suffi- 
cient numbers to threaten their existence. 
The flasks which were opened later served only to corrob- 
orate what has been said. The experiment was repeated 
with the same result. Each of the flasks that were opened 
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