9 2 



THE MECHANISM OF LIFE 



" We are able to produce by diffusion not only the 

 achromatin spindle, but also the segmentation of the 

 chromatin, and the division of the nucleus. If in the saline 

 solution we place a coloured isotonic drop between two 

 coloured hypertonic drops, all the figm-es and movements 

 of karvokinesis appear successively in their due order. The 

 central drop, representing the nucleus between the two lateral 



drops or centrosomes, first be- 

 comes granular. Next we see 

 what appears to be a rolled- 

 up ribbon analogous to the 

 chromatin band, which soon 

 breaks into fragments analo- 

 gous to the chromosomes. 

 These arrange themselves 

 around, and are gradually 

 attracted towards the cen- 

 trosomes. where tliev accumu- 

 late to form two pigmented 

 nuclear masses. A partition 

 then makes its appearance in 

 the median line, and this 

 partition becomes continuous 

 with the boundary of the 

 spheres around the centro- 

 somes. Finally we have two 

 Fig. 32.— Four successive stages in ^lls m juxtaposition, each 

 the production of artificial karyo- with its nucleus, its proto- 

 kinesis by diffusion. plasm, and its enveloping 



membrane. I have been able 

 to photograph these successive stages of the segmentation of 

 the chromatin just as I have those of the achromatin spindle" 

 (Fig.*.'). 



This memoir, written in 1904, clearly asserts the homo- 

 polaritv of the centrosomes, and shows that the nuclear 

 division is the result of a bipolar action, two poles of the 

 same sign exerting their influence on opposite sides of the 

 nucleus. It also emphasizes the important fact that diffusion, 



