274 WATASE. [Vol. IV. 



as first arising from the achromatic portion of the original 

 nucleus, to which, by osmotic action, is added the substance 

 from the surrounding cytoplasm. 



While Strasburger regards the " Verbindungsschlauch " as a 

 mechanism for separating the two daughter chromatic "plates" 

 apart, he also ascribes to the latter a certain automatic capacity 

 for movement. The chromatic threads may probably use the 

 spindle filaments as supports in the course of their migration. 

 Strasburger also supposes that the poles of the spindle exert a 

 certain influence upon the behavior of the chromatic threads. 

 " In welcher Art man sich die Wirkung der Pole denken mag, 

 kommt dabei zunachst nicht in Betracht, es ware ja moglich, 

 dass es sich dabei um einen chemischen Reiz handelt, ahnlich 

 demjenigen, der die Plasmodien, Bacterien oder Oscillaria- 

 Faden veranlasst, bestimmte Bewegungsrichtungen einzu- 

 schlagen" (p. 153). 



Strasburger then recognizes four possible factors which de- 

 termine the movement of the chromatic threads: (i) Spindle 

 fibres, cytoplasmic in origin, penetrating the nucleus, through 

 the nuclear membrane; (2) the "Verbindungsschlauch," partly 

 nuclear, partly cytoplasmic in origin, driving the two daughter 

 chromatic plates wider apart towards the poles of the spindle ; 

 (3) the chromatic granules forming the nuclear threads having 

 an automatic power of movement, and travelling themselves 

 towards the poles, using the achromatic spindle fibres as sup- 

 ports ; and (4) the poles may exert a certain influence upon the 

 migrating chromatic threads, whose nature is difficult to imagine, 

 but may possibly be chemical in its nature. 



There are a few more theories recently published, attempting 

 to explain the phenomena of caryokinesis on a mechanical 

 ground. The main object of the present paper not being to 

 discuss caryokinesis, I cannot enter into a fuller examination of 

 different views on the subject at present. 



To turn again to the description of the caryokinetic process 

 in Cephalopod. As to the filamentous nature of the interzonal 

 substance, there can be no question, as several observers have 

 abundantly shown. My own studies on Cephalopods and Echi- 

 noderms have convinced me of the truth of this conclusion. 

 Further, no optical difference could be observed between the 

 archoplasmic fibrils at the poles of the spindle and the filamen- 



