326 The Morality of Nature 



of the internal tie or bonding forces ; divides into two parts 

 which pass and stand one on each side of the nucleus. They 

 seem to pull the nucleus apart. The nucleus arranges itself 

 for division by grouping its chief substance (called the 

 chromatin) into short sections called chromosomes, of 

 definite number for each different species. This substance 

 becomes a long cord which breaks into the sections — always 

 four or six or twelve or whatever the racial number may be. 

 These, like little strings of beads, divide as if each bead 

 was split sideways to make two parallel thinner strings, then 

 each half string goes opposite ways, so that the two centro- 

 somes get exactly half of each bead or knot of nuclear sub- 

 stance; not one half in number only, but half of each sec- 

 tion, and half of every single bead or knot, so that any 

 quality peculiar to one knot is divided equally; for every 

 such knot. Then the whole cell divides, by becoming of 

 dumbbell shape, with a half centrosome and half nucleus in 

 each bulb, and by separating in the middle. Each centro- 

 some and nucleus becomes independent, and there are two 

 new cells. Now it has been seen and shown that the division 

 of the nucleus, thus wonderfully adjusted, awards to each 

 new cell its absolutely fair share of the heredity. That is to 

 say, that the parent cell is endowed with and transmits 

 certain capacities to do certain work, and to produce certain 

 tissues in certain shapes; not only to reproduce itself, but, 

 in due course to produce various successive changing forms 

 unlike itself, to suit special duties; and thus to build up the 

 various parts of a body, in case the parent cell had such a 

 body. For example the cells performing the regular func- 

 tion in the limb of a salamander, which usually grow thigh 



