THE EFFECT OF ALCOHOL ON GASTRULATION IN ARBACIA

¹ From the Thompson Biological Laboratory, Williams College, and the Marine Biological Laboratory, Woods Hole, Mass.

The general effect of immersing the blastula and young gastrula stages in various concentrations of methyl, ethyl, isopropyl, propyl, butyl, amyl and capryl alcohols for 5-18 hours is a depression of gastrulation and development which is conditioned by the kind of alcohol, the concentration and the length of exposure. They all give quite similar effects but within narrower limits for the higher ones.

Apparently the process of gastrulation is no more sensitive to the alcohols than other developmental processes. It may be inhibited for 5-18 hours without the ability or vigor of gastrulation being diminished. The stage of gastrulation does not express itself as determining the capacity to continue gastrulation in this modified environment. Differentiation without gastrulation was not found nor gastrulation without differentiation except in fatally injured embryos. Information is given on the concentrations which caused complete but reversible inhibition of gastrulation and on the limits of alcohol toleration. A slight acceleration of the rate of development was observed in the lowest concentrations of methyl, ethyl and isopropyl alcohols.

Embryonic differentiation is affected by the alcohols. Abnormalities appeared in the development of body form and size, length of the arms, and structure and amount of the skeleton. Ciliary activity is not inhibited in concentrations which stop development but the rate is reduced. Fusions appeared in the cultures but only those involving two individuals underwent any considerable differentiation. Few exogastrulæ were found and they were always of a shallow type which did not differentiate to any extent. This abnormality appeared among the more susceptible individuals in the lower concentrations of the alcohols.