ANALOGIES AMONG INFERIOR STRUCTURES. 387 



lowest sense : there is no subordination of parts among 

 them — no organization. Each of the component units 

 lives by and for itself; neither giving nor receiving aid. 

 There is no mutual dependence, save that consequent on 

 more mechanical union. 



Now do we not here discern analogies to the first 

 Btages of human societies ? Among the lowest races, as the 

 Bushmen, we find but incipient aggregation : sometimes 

 single families ; sometimes two or three families wandering 

 about together. The number of associated units is small 

 and variable : and their union inconstant. No division of 

 labour exists except between the sexes ; and the only kind 

 of mutual aid is that of joint attack or defence. We see 

 nothing beyond an undifferentiated group of individuals, 

 forming the germ of a society ; just as in the homogeneous 

 groups of cells above described, we see only the initial stage 

 of animal and vegetal organization. 



The comparison may now be carried a step higher. In 

 the vegetal kingdom we pass from the Thallogens^ consist- 

 ing of mere masses of similar cells, to the Acrogens, in 

 which the cells are not similar throughout the whole mass ; 

 but are here aggregated into a structure serving as leaf, 

 and there into a structure serving as root : tlius forming a 

 whole in which there is a certain subdivision of functions 

 among the units ; and therefore a certain mutual dependence. 

 In the animal kingdom we find analogous progress. From 

 mere unorganized groups of cells, or cell-like bodies, we 

 ascend to groups of such cells arranged into parts that 

 have different duties. The common Polype, from whose 

 substance may be separated individual cells w^hich exhibit, 

 when detached, appearances and movements like those of 

 the solitary Amceha^ illustrates this stage. The compo- 

 nent units, though still showing great community of char- 

 acter, assume somewhat diverse functions in the skin, in 

 the internal surface, and in the tentacles. There is a cer- 

 tain amount of " physiological division of labour.' ' 



