568 GENERAL PHYSIOLOGY 



be very profitable to treat modern sociology in the light of these. 

 If this were done, doubtless many schemes regarding social reform 

 would result very differently from at present. 



In a cell-community there is nothing living but the cells. The 

 life of the community is merely the expression of the lives of the 

 cells. Hence it is evident that a cell-community can live only 

 when its individual constituents lead suitable lives. The 

 independent vital activity of the individual cell is, therefore, the 

 indispensable prerequisite of the life of the compound organism. 

 But how much of its independence the individual cell gives up in 

 uniting with others is subject to great variation. That it must 

 always give up something is evident when it is borne in mind that 

 by the association of the different cells the external vital conditions 

 of the individual cell become greatly changed. Cells that have 

 permanently exchanged free individual life for life in a cell-com- 

 munity, such as the tissue-cells of the higher plants and animals, 

 usually perish very soon when separated from their associates. 

 The other cells of the community become an external vital condi- 

 tion for the tissue-cell. 



This condition of dependence in which the cells of the community 

 stand to one another is less, and the independence of the individual 

 cell is greater, the lower we descend in the series of organisms, the 

 more the individual cells of the community resemble one 

 another. 



The simplest relations are found among the Protista. Here we 

 find cell-communities of the primitive type of a genuinely repub- 

 lican form of government, in which every cell is like the others 

 and is capable of existing by itself independently of the others. 

 A Carchesium stalk (Fig. 273, /), a Eudorina colony (Fig. 273, //, A }, 

 and a Magosphcera globule (Fig. 273, //, B}, are such true cell- 

 republics. Sometimes the members of these communities separate 

 themselves from one another and lead an independent life. But, so 

 long as they are united, a certain dependence exists even in the 

 genuinely republican community, in spite of the great independence 

 of the individual cells. The individual Carchesium is influenced by 

 its neighbours. If one of its neighbours suddenly contracts, it is 

 likewise made to contract by the shock. The individual Eudorina- 

 or Magosphcera-cell in its movement is likewise dependent upon 

 the others. The stroke of its cilia does not drive it to the place 

 where it would swim if it had free locomotion, but is only one of 

 the many components from which the movement of the whole 

 spherical colony results. 



But the dependence of the cells is much greater in the cell- 

 communities of the plants and the lowest Ccelenterata, which stand 

 upon the same social grade with the plants, than in these cell- 

 republics of the Protista. The government of plants has also been 

 termed republican, in contrast to the more monarchical govern- 



