130 N. YATSU. 



my conclusion. He obtained through the section near the ani- 

 mal pole along op (his Fig. 3, B, on p. 240) the animal larva 

 without any apical organ, the vegetative one in this case having 

 been provided with the multiple apical organs (his Fig. 10, E, on 

 p. 433). On the other hand, in another case, he found that both 

 the animal and vegetative larvae had the normal apical organ 



(his Fig. 10, A and B] when he cut along the plane near the 

 equator (kl of his Fig. 3, B]. In this case it may be inferred that 

 the section plane bisected the basis of the apical organ. He 

 gives still another instance of the animal larva with the apical 

 organ (his Fig. 10, C) obtained when he cut below the equator 

 along ;;//;/ (his Fig. 3, -5). 



The pilidium No. 10 (4-D) is a very important one. It was 

 produced from an egg from which about one third of the animal 

 hemisphere was cut off. This was about as large as a perfect 

 larva if seen from the side, but it was extremely compressed 

 laterally. It has not only two apical organs but two guts. I 

 suspect that it might have been disturbed by some unknown 

 cause at the two-cell stage because, as a rule, half-larvae obtained 

 by isolation of blastomeres are larger than one half of the normal 

 larvae. In another pilidium (No. 4) I found the apical organ 

 shifted from the normal position (4^). In spite of this, it swam 

 with the apical pole directed forward like a normal pilidium. 



