Preservation of the Life of the Egg 287 



ripe starfish egg is comparatively greater than in the sea-urchin 

 egg. This is the case since the unfertilized egg of the sea-urchin 

 has a rate of oxidations from four to six times smaller than that 

 found after fertilization; while the ripe but unfertihzed egg of 

 the starfish has a rate of oxidations equal to that of the fertilized 

 egg^ (chap. iii). 



We have another fact in support of our view. We saw in a 

 previous chapter that the artificial membrane formation raises 

 the rate of oxidations in the sea-urchin egg about six times. 

 If our contention that the unfertilized egg is comparable to an 

 anaerobe is correct the membrane formation should hasten the 

 death of the unfertilized sea-urchin egg. This is, as we saw, 

 actually the case. While the unfertilized egg of purpuratus 

 without membrane lives for several days, the unfertilized egg 

 after membrane formation dies at the same temperature in a 

 few hours. Moreover, we saw that the death of the unferti- 

 lized egg after membrane formation is retarded if we inhibit 

 the oxidations in the egg. We pointed out, however, that in 

 this case the oxidations may lead only indirectly to the rapid 

 death of the egg, inasmuch as they set the apparatus of nuclear 

 cell division in motion. We can also save the life of the egg 

 after membrane formation by inhibiting development with 

 chloral hydrate, which does not diminish the rate of oxida- 

 tions.^ 



2. It has been one of the important results of our work to 

 show that for the egg of the sea-urchin, and perhaps in general, 

 the causation of normal development requires as a rule the 

 co-operation of two factors, the membrane-forming factor and 

 the corrective factor. The question arises, which of the two 

 has the life-saving effect? At first sight it would seem as if 

 this important function was to be attributed to the- second 

 factor; for it is the second factor which saves the egg, after 



1 Loeb and Wasteneys, Archiv f. Entwicklungsmechanik, XXXV, 555, 1912. 

 ^ Loeb and Wasteneys, Jour. Biol. Chem., XIV, 517, 1913. 



