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 unfertilized egg of 
the starfish has a rate of oxidations equal to that of the fertilized 
egg! (chap. il). 
We have another fact in support of our view. We saw ina 
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. 
2 Loeb and Wasteneys, Jour. Biol. Chem., XIV, 517, 1913. 
