2 OF THE LIVING HUMAN BODY. 



fluids — to propel the fluids — and perform various other 

 motions ; and which, as they, in a certain sense, con- 

 stitute the essence of the living machine in general, so 

 also are of very different orders — some being common 

 to animals and vegetables — some peculiar to animals 

 and intimately connected with the mental faculties. 



2. But these three, although really distinct, and 

 therefore distinctly considered by us, are so closely 

 related in the living system, (the phenomena, conditions, 

 and laws of whose functions, in the healthy state, are 

 the object of physiology) that no one can be contem- 

 plated but in its relation to the rest. 



For the materials of the body, although originally 

 fluid, are naturally disposed to become solid ; and, on 

 the other hand, the solids, besides having been formed 

 from the fluids, abound, however dry they may appear, 

 in various kinds of fluid constituents, both liquid and 

 aeriform : lastly, it may probably be affirmed, that no 

 fibril, during life, is destitute of vital power. 



3. We shall now examine each of these separately ; 

 and first, the materials afforded by the fluids, which 

 form both the fundamental and most considerable por- 

 tion of our bodies.* 



* The great preponderance of the fluids is strikingly exemplified in an entire, 

 but perfectly dry, mummy of an adult Guanche, one of the original inhabitant* 

 of the island of Tenerifte. It was sent to my anatomical museum by the illus- 

 trious Banks, and, though all its viscera and muscles are preserved, docs not 

 exceed 7£lbs. in weight. 



