THE EFFECT OF VERY DILUTE ETHYL ALCOHOL UPON THE RATE OF CELL DIVISION

RESULTS OF MEASUREMENTS ON EGGS OF THE MARINE WORM, URECHIS

¹ From the Department of Zoölogy and the Hopkins Marine Station, Stanford University

1. Alcohol has no effect on the rate of cell division of Urechis eggs except to retard and inhibit. In 2 per cent alcohol the first cell division is inhibited, although the nucleus usually divides.

2. In 1 per cent alcohol the time lapse to first cleavage is increased approximately 15 per cent. In 1 per cent alcohol it is increased approximately 3.5 per cent. (See Table I.)

3. A series of sub-narcotizing concentrations of alcohol covering the range per cent to 1/64 per cent does not stimulate the rate of cell division nor affect it within limits of 1 per cent (see Fig. 1).

4. This covers the ranges in which stimulation to the extent of 30 per cent or more has in some cases been observed in Protozoa. In other cases, with the same and with other protozoan forms, no stimulation has been found.

5. It is suggested that the stimulation in the Protozoa, when it occurs, may be largely a nutritive phenomenon, where food supply is acting as a limiting factor to division rate. This involves the assumption that alcohol may be used as a food either directly or through the medium of microörganisms.

6. The Urechis egg, with self-contained food supply, presumably avoids this limiting factor. It has other points of simplicity for testing the effect of dilute alcohol upon cleavage rate, such as constant medium, which are discussed. The varying and apparently contradictory results of different investigators with the Protozoa and the results with Urechis eggs can be placed tentatively in agreement if certain assumptions are made.