STUDIES OF REPRODUCTIVE ELEMENTS: II. 31 D 



than live-hundred spore« in a very large animal, while in other cases 

 the number wns little over three-hundred. lUit this also is not al- 

 ways the case, for the area c<3vered by the spores varies in different 

 individuals, though in usumI cases it is nearly one-lialf to one-tliird of 

 the half surface of the cell. 



We will now speak about some pnnts of more or less interest in 

 the phenomena displayed in the karyokinetic division of the cells of 

 other animals com])ared with those presented in the above described 

 cell-division of Noctiluca. These points concern the archoplasm, 

 the C'KXTROSOME, and the spixdle fibres. 



The ARcnopj.ASM is, as will have been seen from the in-ecedinf 

 description, first generally found quite near the nucleus when this is 

 in pre[.aration to divide, (see Fig-s. 1, 2, 13, 31 etc.). At this time 

 the nuclear wall is always distinctly to be seen, and the size of the 

 archoplasm as com])ared witli that of the nucleus is such as to make 

 its origin from the nucleoplasm very improbable. The nucleus at 

 this stage and in the living condition, appears more or less homo- 

 geneous and transparent, wliile the archoplasm, consisting of coarse 

 granules, is so conspicuous as to be easily mistaken for it. This fact 

 perhaps explains tlie statements oi'Cienkowshj ( 8, p. 54), who supj)oses 

 the nucleus to disappear at tlie beginning of the spore-formation in 

 tlie animal. JUnn (6, p. 1070) lias observed the archoplasm and the 

 changes it passes through in nuclear division, but seems to have 

 mistaken it for the nucleus. In dividing individuals, the archoplasm 

 remains closely attached to the nucleus and for a, long time until 

 the complete separation of the daughter individuals, as will be 

 seen in Fig. 12; and in spore-forming animals up to the time 

 when the spore is ready to swim away from the surface of the 



