2/2 WATASE. [Vol. IV. 



daughter stars. For the graphic illustrations of this view, the 

 reader is referred to the diagrams constructed by Boveri.^ 



Boveri's^ view on the origin of the interzonal filaments in 

 Ascaris is a remarkable one. He agrees with van Beneden in 

 regarding the interzonal fibrils as essentially different from the 

 archoplasmic spindle fibres. In fact, Boveri does not regard the 

 interzonal filaments as filaments at all, but simply as the optical 

 expression of longitudinal folds of the ^' lavie interniediaire'' of 

 van Beneden, brought about by the contraction of the archo- 

 plasmic fibrils, whose distal extremities are fastened to the chro- 

 mosomes of the nucleus, and the consequent stretching of the 

 intermediary lamina in the longitudinal direction of the spindle. 

 The folds thus produced run parallel with the longitudinal axis 

 of the caryokinetic figure, and give rise to the filamentous ap- 

 pearance. Boveri admits that the interzonal filaments in the 

 caryokinetic figures in other cells, demand a different explana- 

 tion from that given above. 



It would be entirely out of place here to enter into the exami- 

 nation of the details of the phenomena so admirably brought out 

 by Boveri. But before leaving Boveri I would like to call atten- 

 tion to his Fig. 41,2 Taf. XX, in the above-mentioned memoir, 

 in which a group of archoplasmic threads from the upper centre 

 fasten themselves to two chromatic loops in common with some- 

 what longer archoplasmic threads arising from the opposite 

 centre. 



The figure suggests the idea that the upper bundle of archo- 

 plasmic threads are yielding to the greater pushing force of the 

 lower. If the archoplasmic fibrils are contractile in movement 

 during the stages of metakinesis, and are pulling the chromo- 

 somes towards their own archoplasmic centres, how does it 

 happen that this bundle shows such a peculiar curvature, its 

 convex surface being turned away from the centre which is sup- 

 posed to be the centre of attraction .-' 



Another point I would like to observe in connection with the 

 theory of van Beneden and Boveri on the function of the archo- 



1 Boveri : Zellen-Shidien, IJ. Jenaische Zeitschrift, Bd. XXII, Taf. XXI, Figs. 

 64 «, bifb. See, also, Geddes and Thompson: The Evolution of Sex, p. 222. Lon- 

 don, 1889. 



2 Boveri : loc. cit. 



3 Reproduced in Geddes and Thompson : The Evolution of Sex, p. 146, Fig. 3. 



