.STUDIES OF REPRODUCTIVE ELEMENTS: II 393 



Brauer (4', consider tlie ycrhiNdiiiKjstadcH to be formed from tlie /?'//?7?- 

 substance l)y the separation of the chromosomes towards the poles of the 

 spindle. Accordino- to Stra!ihur(icr (36, p. I8ö), these are formed from 

 tlie same substance as the kinetic tibres, which enter from the poles 

 of the spindle and meet in the equatorial plane. This view accords 

 well witli tliat of Hermann, in so far that the latter author considers 

 the central spindle as forming the ]'erhinilungsjaden of other investiga- 

 tors. Tn s{)iteofthe great similarity between the structures of the 

 spindle in Noctiluca and Salamandra this view oï Hermann's con- 

 cerning the ^'erhindnngsfäden can not l)e ap]>lied in explanation of the 

 same structure in the Noctiluca s[)indle, since, as we see from the 

 above description, the persistence of the nuclear wall in Noctihica 

 naturally shnts off all possibihty of confounding the libres of the 

 central spindle with those extending between the free ends of tlie 

 separating chroiiK^somes. Moreover, the two sets of fibres opticallv 

 appear quite di itèrent from each other, as will be seen in Fig. 37, (c.f.) 

 and (/■./.). 



Of the origin of the radial tibres in Noctiluca, I can say but 

 a few words, since the whole pr<)blem still remains very obscure 

 and requires a thorough study with better methods and optical instru- 

 ments.' In sections given above, these tibres. whicli are found within 

 the nucleus and probably attached to the chromosomes, appear to come 

 into close juxtaposition, but not to be continuous with those without, 

 i.e., those seen within and without the nucleus appear to be diiferent 

 from each other, the f )i-mer originating from the nucleoplasm and the 

 latter from the cyto])lasm, just as Braver thinks concerning the forma- 

 tion of the spindle fibres of Ascaris megalocepha la bixalens 

 (4, p. 182-183). 



1 . It may be here remarked that our climate is not fitted for the use of Zeiss apochromatic 

 systems, the dampnoss of the air in the warm season soon blunging- considérai )]<_■ alterations in 

 the lenses. 



