AND FUNCTIONS OP ANIMALS, &-C. 49 



ble ; thick, thin, salt, bitter, sweet : And if from our own 

 we pass to other species of animals, we find amongst theii 

 secretions not only the most various, but the most opposite 

 properties ; the most nutritious aUment, the deadliest poi- 

 son ; the sweetest perfumes, the most fetid odours. Of 

 these the greater part, as the gastric juice, the saliva, the 

 bile, the slippery mucillage which lubricates the joints, the 

 tears which moisten the eye, the wax which defends the 

 ear, are, after they an^ secreted, made use of in the animal 

 economy ; are evidently subservient, and are actually con- 

 tributing to the utilities of the animal itself Other fluids 

 seem to be separated only to be rejected. That this also 

 is necessary (though why it was originally necessary, we 

 cannot tell) is shown by the consequence of the separation 

 being long suspended ; which consequence is disease and 

 death. Akin to secretion, if not the same thing, is assim- 

 ilation, by which one and the same blood is converted into 

 bone, muscular flesh, nerves, membranes, tendons ; things 

 as different as the wood and iron, canvass and cordage, of 

 which a snip with ijs furniture is composed. We have no 

 operation of art wherewith exactly to compare all this, for no 

 other reason perhaps than that all operations ot art are ex- 

 ceeded by it. No chemical election, no chemical analysis oi- 

 resolution of a substance into its constituent parts, no me- 

 chanical sifting or division, that we are acquainted with, in 

 perfection or viriety, come up to animal secretion. Never- 

 theless, the apparatus and process are obscure : not to say, 

 absolutely concealed from our inquiries. In a few, and only 

 a few instances, we can discern a little of the constitution of 

 a gland. In the kidneys of large 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 substance of wbich bodies 

 the secret of the machinery seems to reside, for there the 

 change is made. We can discern pipes laid from these 

 round bodies towards the pelvis, which is a basin within 

 the solid of the kidney. (PI. VI. fig. 2.) We can discern 

 these pipes joining and collecting together into larger pipes; 

 and when so collected, ending in innumerable papillae, 

 through which the secreted fluid is continually oozing into 

 its receptacle. This is all we know of the mechanism of 

 a gland, even in the case in which it seems most capable of 

 being investigated. Yet to pronounce that w^e know noth- 

 ing of animal secretion, or nothing satisfactorily, and with 

 Jliat concise remark to dismiss the article from our argii- 



