64 NATURAL THEOLOaY. 



ble properties, in taste, sijiell.. color, and consistency, the 

 most unlike one another tliat is possible — thick, thin, salt, 

 bitter, sweet : and if from mr own we pass to other species 

 of animals, we find among their secretions not only the most 

 various but the most opposite properties ; the most nutri- 

 tious aliment, the deadliest poison ; the sweetest perfumes, 

 the most fetid odors. Of these the greater part, as the gas- 

 tric juice, the saliva, the bile, the slippery mucilage which 

 lubricates the joints, the tears which moisten the eye, the 

 "svax which defends the ear, are, after they are secreted, 

 made use of in the animal economy, are evidently subservi- 

 ent, and are actually contributing to the utilities of the ani- 

 mal itself. Other fluids seem to be separated only to be 

 rejected. That tliis also is necessary — though why it was 

 originally necessary we cannot tell — is shown by the conse- 

 quence of the separation being long suspended, which con- 

 sequence is disease and death. Akin to secretion, if not the 

 same thing, is assimilation, by which one and the same blood 

 is converted into bone, muscular flesh, nerves, membranes, 

 tendons ; things as diiierent as the wood and iron, canvas 

 and cordage, of which a ship with its furniture is composed. 

 We have no operation of art wherewith exactly to compare 

 all this, for no other reason, perhaps, than that all opera- 

 tions of art are exceeded by it. No chemical election, no 

 chemical analysis or resolution of a substance into its con- 

 stituent parts, no mechanical sifting or division that we are 

 acquainted with, in perfection or variety, come up to animal 

 secretion. Nevertheless, the apparatus and process are ob- 

 scure, not to say absolutely concealed from our inquiries. 

 In a few, and only a few instances, we can discern a lit- 

 tle of the constitution of a gland. In the kidneys of laro-e 

 animals, we can trace the emulgent artery dividing itself 

 into an infinite number of branches ; their extremities every- 

 where communicating with little round bodies, in the sub- 

 stance of which bodies the secret of the machinery seems to 

 reside, for there the change is made We can disoern pipes 



