590 APPENDIX A. 



this. The tendency to separate is the tendency not to act 

 together, probably arising from inability to act together any 

 longer ; and the process of separation is the process of ceasing to 

 act together. How truly non-co-ordination is the essence of the 

 matter will be seen on observing that fission takes place more or 

 less rapidly, according as the co-ordinating apparatus is less or 

 more developed. Thus, " the capability of spontaneous division 

 is one of the most distinctive attributes of the acrite type of 

 structure ; " * the acrite type of structure being that in which the 

 neurine or nervous matter is supposed to be diUused through the 

 tissues in a molecular state, and in which, therefore, there exists 

 no distinct nervous or co-ordinating system. From this point 

 upwards the gradual disappearance of spontaneous fission is 

 clearly related to the gradual appearance of nerves and ganglia — 

 a fact well exemplified by the several grades of Annelida and 

 Myriapoda. And when we remember that in the embryotic 

 development of these classes, the nervous system does not make 

 its appearance until after the rest of the organism has made 

 great progress, we may even suspect that that coalescence of 

 segments characteristic of the Myriapoda^ exhibits the co-ordi- 

 nating power of the rapidly -growing nervous system overtaking 

 and arresting the separative tendency ; and doing this most 

 where it (the nervous system) is most developed, namely, in the 

 head. 



And here let us remark, in passing, how, from this point of 

 view, we still more clearly discern the antagonism of individuation 

 and reproduction. We before saw that the propagation of the 

 race is at the expense of the individual : in the above facts we may 

 contemplate the obverse of this — may see that the formation of 

 the individual is at the expense of the race. This combination of 

 parts that are tending to separate and become distinct beings — 

 this union of many incipient minor individualities into one large 

 individuality — is an arrest of reproduction — a diminution in the 

 number produced. Either these units may part and lead inde- 

 pendent lives, or they may remain together and have their actions 

 co-ordinated. Either they may, by their diffusion, form a small, 

 simple, and prolific race, or, by their aggregation, a large, com- 

 plex, and infertile one. But manifestly the aggregation involves 

 the infertility ; and the fertility involves the smallness. 



§ 9. The ability to multiply by spontaneous fission, and the 

 ability to maintain individual life, are opposed in yet another 

 mode. It is not in respect of size only, but still more in respect 

 of structure, that the antagonism exists. 



* " A General Outline of the Animal Kingdom." By Professor T. R. 

 Jones, p. 61. 



