On the nature of the process of fertilization

Abstract

Two years ago I showed that the process of natural fertilization of the sea urchin egg could be imitated by the combination of two agencies: first the artificial production of a membrane around the egg and second the treatment of the egg for some time with hypertonic sea water. I expected that this imitation of the natural process of fertilization by external agencies might lead to a discovery of the ultimate chemical character of the process of fertilization and this proved to be true to that extent that I was able to show in a series of papers, published a year ago, that the essential effect of the natural or artificial fertilization is a calling forth of oxidations in the egg. These oxidations are the prerequisite for the synthesis of nuclein compounds from protoplasmic constituents of the egg, and this synthesis which forms the first stage in the developmental process. It may be that the formation of nucleins is an oxidative synthesis. 1

When we produce artificially a membrane around the egg by treating the latter for a couple of minutes with a monobasic fatty acid, the egg forms after a certain time two astrospheres, but begins to disintegrate very rapidly. If the temperature is very low it may segment and even reach a blastula stage. I was able to show that the development as well as the disintegration only occur in the presence of free oxygen. If we substitute carefully washed hydrogen for the air in the sea water or if we prevent the oxidations in the egg by the addition of a trace of KCN to the sea water the eggs will neither develop nor disintegrate. From this I concluded that the process of membrane formation calls for or accelerates in the egg oxidations which lead to the formation of the two astrospheres and - if the temperature be sufficiently low — to a series of cell divisions.