294 The Unity of the Organism 



vertebrates, perform a great number of voluntary acts. In 

 such cases as those of the voluntary muscles, the muscle 

 cells are used by the living being for its needs as strictly 

 as are the whole muscles or the limbs and other primary 

 voluntary members of the bod3^ 



But wliile the functional subordination of cells to the 

 living being is seen most conspicuously in the active use of 

 them by the higher animals as they perform their voluntary 

 acts, this sort of subordination is exceptional, taking the 

 whole world and all its operations together. The most funda- 

 mental, and as it seems, the strictly universal aspect of the 

 functional subordination of cells is in the assimilation of 

 food and concomitant breaking down of synthesized organic 

 substances to produce the basal processes distinctive of each 

 individual and kind of living being. In its metabolic proc- 

 esses the living being's supremacy over its cells is most uni- 

 versally manifest. The identity, structural and functional, 

 which the individual organism maintains by converting nu- 

 trient matter into its own self, and for its own use, is ac- 

 complished largely if not wholly by means of its cells. 



The supposition that the cells themselves, taken inde- 

 pendently of the organisms* to which they pertain, have 

 power to develop and perform the metabolic operations 

 characteristic of eacli species and each individual organism, 

 seems a necessary consequence of the cell-theory in its full 

 modern development, in the conception, that is, which sees 

 in the cell the "key to all biological problems." But it is 

 hardly necessary to remark that there is not an iota of di- 

 rect evidence that cells possess such power. The only obser- 

 vations we have upon which such an interpretation could be 

 forced, even by the most intellectually unscrupulous metli- 

 ods of forcing evidence, are tliose on tlie viabiHty of isolated 

 cells and tissues (see Chapter 6). 



As a matter of fact the evidence from tliis source not 

 only does not support the doctrine of the supremacy of 



