292 THOS. H. MONTGOMERY, 



up of numerous very delicate fibres, while there were no pole radiations \ 

 the chromosomes, in their definitive form and number, lay irregularly 

 in the nuclear cavity. In this cell the spindle lay in the section 

 beneath the nucleus, close to the cell wall, so that it could not be 

 determined whether the nuclear membrane had disappeared in its 

 vicinity (Fig. 14). I was unable to find any stages between the last 

 described, and that of the completed monaster, except that of Fig. 15. 

 The central spindles are exceedingly delicate structures, and to be 

 seen only when they lie exactly in the plane of the section. 



In the monaster stage the 28 rod-shaped chromosomes come 

 gradually to lie more or less regularly with their long axes in the 

 plane of the equator (Figs. 14 — 21). From each centrosomo to each 

 chromosome pass apparently two delicate mantle fibres; at this stage 

 it is practically impossible to determine whether there are still per- 

 sisting central spindle fibres on account of the dense grouping of the 

 chromosomes. The whole achromatic spindle figure is very delicate 

 in the spermatogonia. The chromosomes lie throughout the plane of 

 the equator, and the most peripheral are radially disposed (pole views. 

 Figs. 22—36). 



3. The Sperm atogonic Metakiiiesis. 



The chromosomes are longitudinally halved in this metakiuesis. 

 The splitting takes place in such a way, that the split starts at one 

 end of the chromosome and then gradually proceeds to the other, so 

 that the chromosome opens like a V with the angle of the V placed 

 in the equator and its arms directed towards the poles of the spindle 

 (Figs. 38 — 46). So the daughter chromosomes remain united at one 

 end in the plane of the equator, while their other ends are being 

 pulled towards the spindle poles; later they may together form a 

 straight line parallel to the axis of the spindle, while their point of 

 contact remains in the equator. In the case where a chromosome is 

 much bent, the process of metakinesis is the same as in the straight 

 chromosomes, except that the daughter products are apt to be cor- 

 respondingly bent; but even in the case of the straight chromosomes, 

 the daughter chromosomes frequently become more or less curved, 

 probably due to the tension of the mantle fibres. Finally the con- 

 necting points of the daughter chromosomes separate, and between 

 these ends of the chromosomes a connective fibre is found stretched out, 

 a product of the linin contained within the chromosomes (Figs. 44 

 —48). 



