59 



of advancement or degradation ; organization being constantly simplified, 

 In descending from man to the inferior creatures ; but rising In complex- 

 ity, in re ascending from those animals to man, who is the most complex 

 being in nature, and was justly considered, by ancient philosophy, as the 

 master-piece of the Creator. 



If the intimate structure of our organs totally eludes our investigation, 

 it is, that the finest and most delicate of their constituent parts are of such 

 minute dimensions, that our senses have no hold on them. It is then 

 well to have recourse to analogy, and to study the organization of ani- 

 mals that exhibit the same organs on a larger scale. Thus, the cellular 

 texture of the lungs, which cannot be distinctly shown in man, on account 

 of the extreme minuteness of the smallest bronchise, may be satisfactorily 

 seen in the vesicular lungs of salamanders and frogs. In like manner, the 

 scales which cover the bodies of fishes and reptiles, or the legs of 

 birds, give us a just idea of the structure of the epidermis, and of the 

 arrangement of its small scales, which lie over each other, in a part of 

 their surface. 



The human structure being more complicated, must produce effects 

 more numerous, and results more varied, and more difficult to under- 

 stand. In commencing the study of the animal organization by that of 

 man, we do not therefore, follow the analytic method, we do not proceed 

 from what is simple, to what is more complex. It would perhaps be an 

 easier and a more natural way of arriving at a solution of the grand and 

 difficult problem of the animal oeconomy, to begin by explaining its most 

 simple terms; to rise by degrees from plants to vegetating animals, as 

 polypi; from these to white-blooded animals, then to fishes and reptiles; 

 from the latter to warm-blooded animals, and lastly, to man himself, 

 placed at the head of that long series of beings whose existence becomes 

 complicated, in proportion as they approach him. 



The study of every part of natural history, and especially of Compara- 

 tive Anatomy, cannot fail, therefore, to prove of infinite advantage to the 

 physiologist; a truth well expressed by the eloquent M. de Buffon*, who 

 says, that if there existed no animals, the nature of man would be still 

 more incomprehensible. 



I shall say nothing of the well-known relations of physiology to medical 

 science, of which it is justly considered as the base or support. Medi- 

 cine, called by some the art of healing, by others more properly, the art 

 of treating diseases, may be defined the art of preserving health of curing 



the atom to the most exalted of cherubim. Without carrying it so high or so low, if 

 \ve confine it to the natural beings with which we are well acquainted, and which can 

 be brought under observation, it will be seen, that the idea is not so chimerical as some 

 writers of most respectable authority have supposed it. The plan traced by C. Bonet is 

 evidently defective ; we find in it beings set beside each otlrer, that have but faint lines 

 of resemblance, or altogether illusive. The present state of the natural sciences would 

 allow of its being better done : one might try at least for all bodies what Jussieu has 

 executed with regard to vegetable productions ; and if this undertaking, in the hands of 

 men the most able to bring it to a successful termination, left any thing defective, would 

 not that imperfection be an indication of the existence of other worlds, or of lands yet 

 unknown on the globe ws inha*bit ; undiscovered regions where those animals, and 

 plants and minerals would be fo%nd which were wanting to fill up the gaps in the im- 

 mense series of co- ordinate existence. Demonstratum fuit et hoc, nullam rent contraries, 

 vel omnino multum differentes, quaUtates recipere posse, nisi per media prius iter fecerit. 

 GALENUS de usu partium, lib iv. cap. 12. Author's Note. 



* Histoire Nat torn. V. 12mo. p. 241. Discours sur la nature des anitnaux. 



