y6 Society for Experimental Biology and Medicine. 



52 (195) 



On the nature of the process of fertilization. 



By JACQUES LOEB. 



[From the Herzstein Research Laboratory of the University 

 of California.] 



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 hyper- 

 tonic sea water. I expected that this imitation of the natural 

 process of fertilization by external agencies might lead to a dis- 

 covery of the ultimate chemical character of the process of fertiliza- 

 tion 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 de- 

 velopmental 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 oxida- 

 tions 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. But these oxidations lead also to the 



M.oeb: Biochemische Zeitschrift, i, p. 183, I906; ii, p. 35, 1906. University of 

 California publications, iii : p. I, p. 33, p. 39, p. 49, 1906. PJluger" s Archiv, cxiii, 

 1906. 



