258 STUDIES IN GENERAL PHYSIOLOGY 
I brought them back into normal sea-water; and now every 
cleavage sphere divided at once into more than two pieces, 
sometimes into eight or even more. 
5. I concluded from the foregoing experiments that in the 
concentrated solution a segmentation of the nuclet might 
take place without any segmentation of the protoplasm, 
Eggs which had been impregnated in normal sea-water were 
brought into the concentrated solution and watched care- 
fully. No segmentation of the protoplasm took place; but 
the nucleus divided, indeed, into two, and then further divi- 
sions followed. I tried, moreover, to see whether the proto- 
plasm of such eggs, if brought back into normal sea-water, 
divided into as many cleavage spheres as there were nuclei 
preformed. I saw, indeed, that every nucleus becomes the 
center of one of these projections, which later on become 
cleavage spheres. Dr. Conklin was kind enough to stain 
some of the eggs which had been in the concentrated solu- 
tion for some time and which showed no trace of segmenta- 
tion. Some of these stained eggs showed very distinctly from 
four to about thirty distinct nuclei. In other eggs the seg- 
mentation of the nucleus was not so perfect. The nucleus, 
extremely enlarged, seemed to consist of several parts, which, 
however, were still connected. These eggs had been killed 
at a time when the eggs of the same lot which had remained 
in normal sea-water all the time were in about the sixty-four- 
cell stage. 
6. Fol and O. and R. Hertwig found that in the case of 
polyspermia the egg at once divides into about as many cells as 
there are asters. We know that for the segmentation of the 
protoplasm it does not make any difference whether the nuclei 
are derived from the male pronuclei exclusively, as in the 
case of the impregnation of an enucleated egg; or from the 
conjugated nuclei, as in the normal case; or from both conju- 
gated nuclei and male pronuclei together, as in some cases 
Digitized by Microsoft® 
