348 The Morality of Nature 



numbers in the units of the nuclear substance, which are 

 called chromosomes. These small groups of chromatin sub- 

 stance which control the heredity, are of variable numbers 

 from two or four in some species, to a hundred or more in 

 others, but the number is always the same in a species, and 

 it has seemed mysterious that the number is always an even 

 number; so that in certain conditions it can be divided into 

 two half cells, as a preliminary to the union of one half cell 

 with another half. Now this circumstance can be supposed 

 to arise in a pre-established habit of conjugation, as a con- 

 dition precedent to sexual ability. 



It is not to be supposed that sex is an original necessity, 

 in fact there are even now prevalent various other modes 

 of reproduction ; and in one-celled creatures sex is obviously 

 of only partial potency, and may be expected to reach only 

 preliminary form. This preliminary form may well be the 

 adoption of the doubled nucleus as the normal; that is to say 

 the stage at which a cell has most stability. The cell arises 

 as the organization of protoplasm with a nucleus. This 

 occurs while that protoplasm is repeatedly dividing in growth 

 of mass of uniform character, and repeatedly reuniting when 

 affinities arise. Now an observed rudimentary cell may 

 present itself, at the stage resulting from a division of 

 former protoplasm ; or it may present a mass, at the stage of 

 the recent addition of two former cells. When we observe 

 the descent of one cell from a parent, the obvious origin by 

 division seems to efface the other possibility. But if we 

 consider that the protoplasmic mass arose first, by the addi- 

 tion of an assimilated unit to a pre-existent unit, it is still 

 more obvious that the fundamental process may be one in 



