FERTILISATION OF THE OVUM 



385 



PLATE LXXXVIII 

 C 



PLATE LXXXVIII {continued) 



M. Chromatin filaments («, h) more widely separated. The central particle of each attraction-sphere (d, d') has now divided 

 into two. 



N. Chromatin filaments («, b) becoming developed into the skeins of daughter nuclei united by achromatic fibres ; protoplasm 

 of ovum dividing into two at x. 



0. X, Division of ovum progressing. The attraction-spheres have now divided into two (d d, d' d'), and are joined by achromatic 

 fibres to each other, and to periphery of cell as at D. The daughter nuclei display a chromatin network. 



PLATE LXXXIX 



Plate Ixxxix. — Dividing nucleus displaying spindle of achromatic fibres with the chromosomes arranged astrally 

 at the equator of the spindle (A). Shows also well-marked radiating and concentric arrangements (Rabl). 



A. a, a'. Central particle ; h, h', polar radiation attraction-sphere ; d, chromatin loop cleft longitudinally ; e, clear area ; 

 /, cell substance. 



B. Dividing nucleus at " aster stage," seen from one of the poles, with the achromatic spindle foreshortened. Shows 

 radiating looped arrangement, a, Outline of nucleus ; /), achromatic spindle with central polar particle ; c, chromatin loops. 



C. to J. Illustrate the stages in the division of the ovum or egg-cell of a worm. Show radiating^ spindle-shaped, concentric 

 arrangements. 



C. Ovum before division. 



D. Spindle-shaped fibres with chromatic nodules (chromosomes) at the equator of the spindle. 



E. Separation of chromosomes into two parts, which travel towards the poles of the spindle and there become transformed into 

 new (daughter) nuclei, the protoplasm meanwhile also separating into two parts, as seen at F, G, H, 



VOL. I, 3 Q 



