Cell Division. 13 



formed from the original one, and by the manner in which the 

 chromosomes divide they consist of an equal number of coloured 

 granules. 



6. And now the sixth and last phase of the complicated proce- 

 dure takes place. Along- the equator of the spindle, and thus mid- 

 way between the two new nuclei, minute particles of matter sud- 

 denly become visible between the spindle threads ; these increase 

 in size and in number, and build across the middle of the dividing 

 cell a wall which always remains pierced with microscopically 

 minute holes, through which protoplasmic threads keep up a means 

 of communication between the severed halves, which are now com- 

 plete and whole cells, sharing the nucleus and the protoplasm of 

 the mother cell equally between them. The threads of protoplasm 

 running through the wall may be regarded as rudimentary nerves, 

 just as the conducting tissue in the stem of a moss is rudimentary 

 xylem and phloem. From many examinations in a number of 

 plants it is now certainly known that by these minute threads each 

 cell of a plant is in direct or indirect communication with all the 

 rest, and we are thus in a position to understand movements 

 formerly considered mysterious, such as when one pinnule of a leaf 

 of the sensitive plant is touched the whole leaf should at once pro- 

 ceed to fold up and hang down on its petiole. 



Professor Schafer would compare this extremely complicated 

 but thoroughly satisfactory mode of division, which results in the 

 two new nuclei being formed, each having an exact share of the 

 original nuclear thread and equal halves of each coloured granule 

 he would compare it with the molecular dance of some particles 

 of carbon suspended in a solution of salt. He says: "Even so 

 " complex a process as the division of a cell nucleus by karyokinesis , 

 " as a preliminary to the multiplication of the cell by division a 

 " phenomenon which would prima facie have seemed and has com- 

 " monly been regarded as a distinctive manifestation of the life of 

 " the cell can be imitated with solutions of a simple inorganic salt, 

 ' ' such as chloride of sodium, containing a suspension of carbon par- 

 1 ' tides ; which arrange and rearrange themselves under the influence 

 "of the movements of the electrolytes in a manner indistinguishable 

 " from that adopted by the particles of chromatin in a dividing 

 "nucleus." But there is not even similarity between the two 



