746 STUDIES IN GENERAL PHYSIOLOGY 
unfertilized starfish eggs is determined by internal condi- 
tions connected with maturation and not by the bacteria 
contained in the sea-water. The proofs for this are: First, 
mature eggs die just as rapidly in sterilized sea-water free 
from bacteria as in unsterilized water, and secondly, when 
maturation is prevented artificially the eggs may continue to 
live in water containing many bacteria. 
3. We have shown that oxygen and free hydroxyl ions 
accelerate the maturation of starfish eggs; that lack of 
oxygen and a neutral or faintly acid reaction of the sea- 
water inhibit or prevent maturation. The fact that the eggs 
which remain immature in the ovaries of the starfish 
maturate when brought into sea-water seems to find its 
explanation in part at least through this. 
4. When the maturation of starfish eggs is prevented 
artificially through lack of oxygen, or the addition of an 
acid to the sea-water, they remain alive much longer than 
when they maturate. The eggs in which maturation has 
already begun, or has just been completed, seem also to be 
saved from rapid death by these means. 
5. It seems to follow from these facts that the same 
chemical processes do not necessarily underlie the process 
of maturation and the process of fertilization. Fertiliza- 
tion by spermatozoa, chemical or physical agencies, lengthens 
the life of the egg, while the changes following the matura- 
tion of the egg lead, sooner or later, to death (through 
autolysis?). Itis in harmony with what has been said that 
the same treatment with acid which brings about artificial 
parthenogenesis in mature starfish eggs inhibits the process 
of maturation when used upon immature starfish eggs. 
6. These facts corroborate a suggestion which I have 
made before, that the fertilizing action of the spermatozoon 
consists in this, that it carries into the eggs substances which 
accelerate the course of certain (synthetical?) processes in 
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