358 Naohide Yatsu. 



ference between these two portions was recently noticed by Bonnevie 

 ('00, p. 282). This seems to show on the one hand that the nuclear 

 fluid contributes to the growth of rays (cf. Mark, '81, p. 53Y), and 

 on the other that a ray may be formed in the nonalveolar plasm 

 {vide infra). The seeminii,' pushing-iu of the nuclear walls at the 

 poles may indicate a passing out of the unclear fluid, at the expense 

 of which the rays grow. 



The nuclear fluid after ^tlie dissolution of the nuclear membrane 

 has a strong resemblance to hyaloplasm, both in its staining reac- 

 tion and in the power of producing rays. While the nuclear fluid 

 is not as a whole identical with the hyaloplasm, one may- say in a 

 general way that the nucleus is a storehouse of hyaloplasm. 



(c) Nucleolus. 



In the germinal vesicle three elements can be seen (PI. I, Fig.l) ; 

 a large plasmosome (principal nucleolus), smaller peripheral plasmo- 

 somes (accessory nucleoli'"') and chromatin masses. 



The larger, plasmosome is usually single, seldom two to four are 

 present (PI. I, Pigs. 1 and 8), and is situated in most cases half 

 way between the nuclear membrane and the centre of the germinal 

 vesicle. In the living state the plasmosome is a drop consisting in 

 most cases of two portions ; one a lenticular or crescentic refractive 

 part, with a reddish tint suggesting the contractile vacuole of some 

 ciliates, and the other a watery part, or "vacuole." The latter is 

 rarely wanting. 



In sections only the denser part comes into view as a solid body, 

 the thinner part being represented either as a clear space contain- 

 ing irregular precipitated masses having the form of small discs 

 resembling mammalian-blood corpuscles (PI. I, Fig. 6), or entangled 

 threads Avliicli stain green with l)leii de lyon (PI. I, Fig. 8). The 

 denser part is usually lenticular or s])horical, but sometimes it 

 gives the appearance of a basket (PL I, Fig. 7). It is homogeneous 

 and takes a deep plasma stain — dark yellowish green with Delafield's 



'^According to Flenuiiing ('82, p. 14(i) the terminology is based simpiy on size, 

 not on chemical nature. 



