Ill 
FERTILIZATION AND OXIDATION 
1. Kighteen years ago the writer showed that if freshly 
fertilized animal eggs (of sea-urchins and fishes) are deprived 
of all oxygen, no nuclear or cell division is possible. Godlew- 
ski? and Samassa? have found the same with frog eggs, and 
since then I have convinced myself that it holds for the eggs 
of the starfish, annelids, molluscs, and probably generally. In 
the same way oxygen is necessary for the maturation of the egg. 
In these experiments on the prevention of development of 
the egg by lack of oxygen, one must guard against a source 
of error which lies in the fact that some time must elapse before 
the air or oxygen has been driven out of the dish containing the 
egg. Since in many forms the first division of the nucleus 
takes place in a little less than an hour, if the temperature is 
high enough, and since it often requires as long, or even a longer 
period, to replace all the oxygen by hydrogen, it may easily 
happen that a nuclear, or even a cell division, may take place 
after the egg has been placed in the stream of hydrogen.‘ I 
avoided this source of error by cooling with ice the vessel con- 
taining the eggs to 0° for as long as appeared necessary from the 
foregoing experiments to replace all the oxygen by hydrogen. 
1 Loeb, ‘‘ Die physiologische Wirkung des Sauerstoffmangels,’’ Pfliiger’s Archiv, 
LXII, 249, 1895. 
2 Godlewski, ‘‘ Die Einwirkung des Sauerstoffs auf die Entwicklung von Rana, 
ete.,”’ Archiv f. Entwicklungsmechanik, XI, 585, 1901. 
3 Samassa, Verhandl. d. naturh.-med. Vereins zu Heidelberg, LV, 1898, and Ver- 
handl. d. deutsch. Zool. Gesellsch., 1896 (quoted from Godlewski). 
4 It must not be taken for granted in general that oxygen is unimportant, if 
the experimenter does not succeed in suppressing all signs of life after a short pas- 
sage of hydrogen or nitrogen through a vessel. It must not be forgotten that it 
takes a long time before the last trace of oxygen is driven out, and that often a 
trace of oxygen is quite sufficient to render possible the life phenomenon under 
investigation. 
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