The writer found that if we keep the unfertilized eggs after artificial membrane formation in sea water deprived of oxygen the disintegration of the egg following artificial membrane formation is prevented for a day at least. The same result can be obtained by adding ten drops of 1/10 per cent. KCN to 50 c.c. of sea water, and certain narcotics, _e. g._, chloral hydrate, act in the same way. Wasteneys and the writer found that chloral hydrate (and other narcotics) in the concentration required do not suppress or even lower the oxidations in the egg to any considerable extent,[98] but they prevent the processes of cell division. Hence it seems that the egg disintegrates so rapidly after artificial membrane formation because it is killed by those processes leading to nuclear division or cell division which are induced by the artificial membrane formation. If we suppress these phenomena of development (for not too long a time) we give the egg a chance to recover and if now the impulse to develop is still active we notice a perfectly normal development. If the egg is kept too long without oxygen it suffers for other reasons and cannot develop; the writer has shown that if eggs fertilized by sperm are kept for too long a time without oxygen they also will no longer be able to develop normally. The short treatment with a hypertonic solution supplies the corrective factor required, so that the egg can then undergo cell division at room temperature without disintegrating. [98] Loeb, J., and Wasteneys, H., _Jour. Biol. Chem._, 1913, xiv., 517; _Biochem. Ztschr._, 1913, lvi., 295.