ARTIFICIAL PRODUCTION or NORMAL LARV.E 609 



egg into a six-cell stage. It is obvious that these cell-divi- 

 sions are accompanied by most striking amoeboid motions, 

 which are characteristic of all the eggs without a membrane. 

 I believe that these amoeboid 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 amoeboid 

 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 amoeboid motions, and I soon afterward ex- 

 pressed the idea that the same is true for the process of cell- 

 division in general. 1 The two nuclei of the mother cell are 

 the centers around which the protoplasm streams and flows. 

 These amoeboid 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 c.c. \^n MgCl 2 +40 c.c. sea-water 



(2) 50 c.c. " +50 c.c. 



(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 



1 LOEB, Archiv filr Entwickelungsmechanik, Vol. I (1895), p. 453. 



