40 AET. 8. T. IKEDA : THREE NEW AND 



by a study of the smaller ones which are apparently in the 

 process of development. With the decrease in size of the bodies, 

 I find that the component cells grow continually less in number, 

 the lobe-like processes of these less pronounced and the internal 

 cavity less spacious. So by a gradational series of transitional 

 forms, the blastula-like bodies are led over to a simple group of 

 a few number of cells (fig. 21 b) which are simply oblong or 

 subspherical in shape and cohere together like blastomeres in a 

 segmenting ovum. Such a small group may be formed of only 

 four or three or even two cells. Each cell then compares well 

 in appearance with the unicellular blood-corpuscle (fig. 39, b.c.) 

 found likewise free in the body-cavity, though generally slightly 

 larger in size. In fact, the identity of the cells referred to seems 

 to scarcely admit of a doubt. It may then be thought of that 

 the polycellular body arises by repeated division of the unicellular 

 corpuscle. And yet, notwithstanding careful researches, I have 

 never been able to detect a sign of cell division in the cells, 

 irrespective of these being isolated or combined. It seems to me 

 not improbable that in view of their extreme poverty in chro- 

 matic substance, the nuclei of the cells in question are in an 

 inactive state as regards the dividing power. If now the poly- 

 cellular bodies are really formed of the unicellular corpuscles, I 

 should think the mode of formation is not by repeated cell- 

 multiplication but by aggregation of the latter in as many 

 number as the body is seen to consist of. 



The " Töpfchen," commonly found in the body-cavity of 

 Gephyrean worms, is in the present species a small globular body 

 provided at one part with a relatively large and ciliated funnel- 

 like opening (fig. 22, fn.). The funnel wall is covered with a 



