54 ON THE STUDY OF ZOOLOGY 



anatomy and physiology, I do not mean to represent to you 

 that the former teaches the latter. Strictly speaking, struc- 

 ture alone is learned by dissection : the vital properties of 

 organic textures, and the functions of organs, are found 

 out by observation. We have the most perfect anatomical 

 knowledge of the spleen, thymus, and thyroid gland ; but 

 their offices in the animal economy are wholly unknown. 

 What organ has been more carefully dissected and studied 

 than the brain ? yet the respective offices of its various 

 portions have not been discovered. 



Anatomy, however, unfolds facts, of which the knowledge 

 is absolutely necessary in appreciating the results of obser- 

 vation. It affords the only clue capable of guiding us 

 through the multiplied and varied movements all going on 

 together in the living microcosm, and of thus enabling us 

 to discriminate the proper share of each organic apparatus. 

 What kind of knowledge could the most patient and acute 

 observer gain of the circulation, if he knew nothing about 

 the structure of the heart, lungs, arteries, and veins ? 

 What insight could he acquire into the changes of the 

 food, and the nutrition of our bodies, if the alimentary 

 canal, with its divisions and appendages, and the absorbing 

 vessels were unknown to him ? Just notions of the seat 

 and nature of diseases, and of the operation of remedies, 

 would be out of the question : but what chance has a 

 person, ignorant of the general construction of our frame, 

 of escaping from the most absurd doctrines and systems, 

 and from the most pernicious practical errors ? 



Anatomy, again, clears up doubtful points, and suggests 

 topics of inquiry : it is a test and criterion of physiolo- 

 gical explanations. If the latter are inconsistent with the 

 anatomical facts, they must be rejected. 



That its aid is essential to physiology may be proved by 

 referring to what even the most acute men have written 

 about the animal economy, before anatomy had been culti- 

 vated. It is a mass of error and fiction, without the smallest 

 pretence to the title of physiology. 



Anatomy and physiology are the ground-work of patho- 

 logy, or the science of disease. 



