Page:Popular Science Monthly Volume 86.djvu/578

574 believe when we bear in mind that the egg may be caused to develop by short exposure to carbonic acid. On fertilization this hypothetical substance would be liberated and could be collected. Glaser fertilized quantities of eggs in a small amount of sea water. On using the same water in which to develop other fertilized eggs, he found it inhibited their development, indicating the presence of an inhibiting substance that came out of the first eggs on fertilization. (Was this ?)

Loeb's "improved method of artificial parthenogenesis" claims two treatments of the eggs to be necessary. They are first to be stimulated to development by use of fatty acid, or some other method, and then exposed to a hypertonic solution. The latter he calls a "corrective agent" and supposes that it changes the character of the oxidation in the egg, since he observes no effect on the rate of oxidation in the developing eggs. It is hard to conceive of such a change in "character," since oxidation means union with oxygen and there is but one kind of oxygen atom in combinations. The oxygen might attack different substances, but in such cases different amounts of heat would be given off, the heat of combustion of fats and carbohydrates, for instance, differing in amount. Meyerhof showed that the ratio of oxygen used to heat produced was the same for eggs in the hypertonic solution as in sea water. When we consider that by the use of either fatty acid or hypertonic solution alone, sea-urchin (Arbacia) eggs may be made to develop, it seems unnecessary to devote more time to their combined effect.

Anesthetics have a depressant action on various cell activities when used in certain concentration. They decrease the respiration and rate of cleavage of sea-urchin eggs (and asphyxiation will cause cleavage to cease). It may therefore be supposed that it is the suppression of oxidation by anesthetics that suppresses cleavage. Warburg, however, caused the almost complete cessation of cleavage in sea-urchin eggs with anesthetics without appreciably lowering the respiration. It may be that the anesthetic acts in one part of the cell (on the surface of the granules) in suppressing oxidation, and in another (on the cell surface) in suppressing cleavage.

In 1909, while measuring the electric conductivity of sea urchins' eggs, the writer observed the decrease in conductivity on the addition of a certain per cent. of chloroform. This experiment was not repeated, but we may imagine that the chloroform decreased the permeability of the eggs to ions. Osterhout, becoming interested in the methods used, modified them for use with plants, and observed a decrease in electric conductivity of certain plants (kelp) when using a certain concentration of anesthetic, indicating that the anesthetic decreased permeability. R. Lillie found that anesthetics might antagonize the action of the pure