242 PROBLEMS OF FERTILIZATION 



In the case of the starfish, however, action of butyric 

 acid alone is sufficient for complete development; a 

 corrective agent is not required. 



If now we ask what is the nature of the postulated 

 cytolysis, and how it activates the egg, Loeb replies 

 that the cytolysis can be explained by assuming that a 

 calcium lipoid compound forms a continuous layer 

 under the surface of the egg; the solution of such a 

 lipoid layer might result in the destruction of a cortical 

 emulsion. It then becomes necessary to assume a cata- 

 lyzer to explain the increase in rate of metaboHsm 

 within the egg, and Loeb therefore suggests, following 

 Warburg (1914), that the cytolysis, by breaking down 

 the cortical emulsion, releases the catalyzer, assumed 

 to be contained in the cortex, for action on the sub- 

 strate. Increase in oxidations results, together with 

 certain synthetic processes. Activation of the egg 

 therefore comes down to the release of a catalyzer; 

 cytolysis is simply the means by which this end is 

 attained. 



The above is the barest possible sketch of Loeb's 

 theory and gives no idea of the numerous experiments 

 carried on year after year since the time of his original 

 discovery of the phenomenon of artificial partheno- 

 genesis in 1899. To get an idea of the wealth of exper- 

 imental data underlying Loeb's analysis the reader 

 must refer to Loeb's own publications, for a brief 

 account to The Organism as a Whole (G. P. Putnam's 

 Sons, 19 1 6), and for a fuller account with numerous 

 references to original papers to Artificial Partheno- 

 genesis and Fertilization (The University of Chicago 

 Press, 1913). 



