£80 



ON THE NUTRITION OF 



that of large ones, and that the minuteness of this 

 system bears some proportion to the diminutive 

 size of the whole body. It is taken for granted, 

 that the circulation may be equally brisk and free 

 as in larger ones. This seems to have been simply 

 inferred from the indefinite divisibility of matter ; 

 and it is true that we are not authorized to set any 

 limits to our conceptions of the minuteness of orga- 

 nic texture. But when we turn our attention to 

 aqueous fluids, we find them governed by this law 

 of capillary attraction, which is susceptible of ad- 

 measurement, and which must impose a limit on 

 the minuteness of the vessels through which streams 

 of such fluids can be transmitted. When hard 

 pressed, indeed, a reasoner who is unwilling to 

 give up such opinions might allege that the circu- 

 lating fluids, in such cases, are not aqueous, but 

 consist of a more tenuious matter, more allied to 

 spirit, governed by a capillary attraction which 

 operates at much smaller distances, or altogether 

 exempt from that influence. Aqueous and oleagi- 

 nous humours, however, are the only ones on which 

 we are entitled to pronounce as existing in animal 

 bodies. Where they differ from pure water, it is 

 not in possessing greater tenuity ; but, on the con- 

 trary, in deriving a greater viscidity from the ani- 

 mal matters with which they are impregnated. 



If any other supposition, therefore, can be main- 

 tained, it may be fairly concluded from these consi- 



