600 STUDIES IN GENERAL PHYSIOLOGY 



3 (100 c.c. y*n CaCl 2 ) had membranes. A few were seg- 

 mented very irregularly into 2 to 3 cells. All the eggs were 

 examined again three hours later. Those that had been in 

 solution 1 were now in a morula stage. As they had no 

 membranes, their outline was very irregular, and I wondered 

 what kind of blastula would result if these eggs ever reached 

 that stage. The eggs that had been in solution 2 (100 c.c. 

 1 - g -?i MgCl 2 ) were without membranes and unsegmented. 

 Of the eggs that had been in solution 3 (100 c.c. y n CaCl 2 ) 

 about 5 per cent, were segmented into from 2 to 4 cells of 

 very unequal size. The last examination had taken place in 

 the evening. The next morning the eggs of solution 1 were 

 teeming with blastulse; some with regular, the majority, how- 

 ever, with most fantastic outlines (see Fig. 149). Their size 

 was very unequal. I expected as much from the irregular 

 appearance of the morulse of the evening before. In the fer- 

 tilized egg the membrane prevents any irregularity in the 

 form of the blastulae. The unfertilized eggs, however, have no 

 membrane, and hence the cells are only kept together by an 

 intercellular substance or by adhesion ; but it is very probable 

 that the processes of cell-division are accompanied by 

 amoeboid motions (Fig. 148), which have the effect of 

 making the arrangement of cells irregular. I have noticed 

 and described this effect of the amoeboid motions of the 

 cleavage cells in my experiments on eggs whose membrane 

 I had caused to burst and whose contents partly flowed out 

 of the egg. 1 These extraovates behaved very much like the 

 unfertilized eggs. In the latter case it was evident from the 

 size of the blastulse that only in rare cases had the whole 

 egg developed into one single blastula. As a rule, each egg 

 gave rise to several blastulae. Through the amoeboid motions 

 connected with the process of cell-division groups of cells 

 became disconnected and developed into dwarf blastulse. I 



1 LOEB, Archivfiir Entivickelungsinechanik, Vol. I (1895), p. 453. 



