CONCERNING BRACKET'S IDEAS OF THE ROLE OF 

 MEMBRANE FORMATION IN FERTILIZATION.^ 



JACQUES LOEB. 



I. A recent publication by Brachet^ seems to make it necessary 

 to discuss once more the relation between membrane formation 

 and development. The writer had shown in 1895 that if oxygen 

 is completely withdrawn from the fertilized sea urchin egg no 

 development is possible, while the moment oxygen is admitted the 

 development can begin again. As he had suggested in 1906 and 

 a,s has since been proved by O. Warburg, and H. Wasteneys and 

 the writer, the entrance of the spermatozoon into the egg of the 

 sea urchin increases the rate of oxidations in the latter (by 400 or 

 600 per cent) . The entrance of the spermatozoon causes also a 

 membrane formation which is very marked in the fresh egg and 

 is generally less marked or may appear to be absent if the egg 

 has been lying in sea water for a day or more. It has been 

 shown, moreover, that the artificial production of a membrane in 

 the unfertilized egg by butyric acid has the same influence upon 

 the increase of the rate of oxidations as the entrance of the 

 spermatozoon. These and other facts seemed to support the 

 view of the writer that an alteration of the surface of the egg, 

 which usually but not necessarily results in a membrane forma- 

 tion, is an essential feature of the development of the egg. 



More recent experiments by Warburg^ have made it very 

 probable that the process of oxidations in the sea urchin egg is 

 a case of catalysis by iron, which is confined mainly if not ex- 

 clusively to the surface; and this fact, in connection with the data 

 mentioned above, seems to indicate that the process which under- 

 lies membrane formation in the unfertilized egg may consist in 

 bringing about or rendering possible the iron catalysis which is 



1 From the Rockefeller Institute for Medical Research, New York. 



2 Compt. rend. I'Acad. d. sc, CLIX., 642, 1914. 

 'Warburg, Zeitschr. f. physiol. Chem., XCIL, 231, 1914. 



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