WASTE AND REPAIR. 183 



out life, the process "by which, repair is carried on. But 

 though cells are so generally the ultimate visible components 

 of organisms, that they may with some show of reason be 

 called the morphological units ; yet, as they are not uni- 

 versal, we cannot say that this tendency to aggregate into 

 specified forms dwells in them. Finding that in many 

 cases a fibrous tissue arises out of a structureless blastema, 

 without cell- formation ; and finding that there are creatures, 

 such as Khizopods, which are not cellular, but nevertheless 

 exhibit vital activities, and perpetuate in their progeny 

 certain specific distinctions ; we are forbidden to ascribe to 

 cells this peculiar power of arrangement. IN'or, indeed, 

 were cells universal, would such an hypothesis be acceptable ; 

 since the formation of a cell is, to some extent a manifesta- 

 tion of this same peculiar power. 



If, then, this organic polarity can be possessed neither b} 

 the chemical units nor the morphological units, we must 

 conceive it as possessed by certain intermediate units, which 

 we may term physiological. There seems no alternative but 

 to suppose, that the chemical units combine into units 

 immensely more complex than themselves, complex as they 

 are ; and that in each organism, the physiological units 

 produced by this further compounding of highly compound 

 atoms, have a more or less distinctive character. We must 

 conclude that in each case, some slight difference of com- 

 position in these units, leading to some slight difference in 

 their mutual play of forces, produces a difference in the form 

 which the aggregate of them assumes. 



The facts contained in this chapter, form but a small part 

 of the evidence which thrusts this assumption upon us. We 

 shall hereafter find various reasons for inferring that such 

 physiological units exist, and that to their specific properties, 

 more or less unlike in each plant and animal, various organic 

 phenomena are due. 



