ARTIFICIAL PRopUCTION OF NormMaL Larva 609 
egg into a six-cell stage. It is obvious that these cell-divi- 
sions are accompanied by most striking amceboid motions, 
which are characteristic of all the eggs without a membrane. 
I believe that these amceboid motions exist in the fertilized 
eggs just as well, but the membrane prevents them from 
becoming so conspicuous as in the unfertilized eggs where 
there is no membrane. In the normal eggs these amceboid 
motions are more symmetrical, and this is another reason 
why they escape our observation. When I made my first 
experiments on the effect of more concentrated sea-water 
upon the segmentation of fertilized eggs, the idea struck me 
that the segmentation by budding (Knospenfurchung) was 
the outcome of amceboid motions, and I soon afterward ex- 
pressed the idea that the same is true for the process of cell- 
division in general.’ The two nuclei of the mother cell are 
the centers around which the protoplasm streams and flows. 
These amceboid motions are only one episode in the process 
of cell-division, for whose full explanation other phenomena 
of an entirely different character must be taken into con- 
sideration. 
Sixth series—The preceding experiment was repeated, 
but this time with due consideration of the fact that the 
eggs must remain long enough (two hours) in the artificial 
solution. The eggs of two females were distributed in three 
solutions: 
(1) 60 cc. 422 MgCl, + 40 c.c. sea-water 
(2) 50 ce. + 50 ce. 
(3) Normal sea-water 
None of the eggs formed a membrane. Some of those 
that had remained in normal sea-water segmented after 
twenty hours. They divided into from 2 to 3 cells and not 
further. I have already mentioned the fact that the unfer- 
tilized eggs of various females differ somewhat in their 
1LoEB, Archiv fiir Entwickelungsmechanik, Vol. I (1895), p. 453. 
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