AND COMPARATIVE ANATOMY. 49 



wslmply organized, that they occupy the lowest rank of animal 

 existence, and indeed have been recognized only, in late 

 times, as falling within the boundaries of the animal king- 

 dom. Their works commence in the fathomless depths of 

 the ocean ; they rise towards the surface, forming sunken 

 rocks, dangerous and often fatal to navigators ; they reach 

 the level of the water, and then extend in length and breadth. 

 When we see that banks are formed of miles in extent, that 

 coasts are obstructed, harbours choked, and even new islands 

 formed, the mind is confounded by the contrast between the 

 insignificance of the agents and the magnitude of the result. 



Other points of view, and other applications of zoology, 

 will be disclosed as we proceed. More perhaps has been 

 already said than was necessary to convince an enlightened 

 audience that the living part of Nature's works is highly 

 worthy of attention ; and that this study, connected as it is 

 with so many useful, interesting, and important depart- 

 ments of knowledge, must be deemed an essential branch of 

 liberal education. 



To these considerations, which recommend zoology, not 

 only as a highly interesting, but essential branch of general 

 knowledge, many others may be added, enforcing the cul- 

 tivation of comparative anatomy and physiology more par- 

 ticularly on those who devote themselves to the improve- 

 ment of medicine. The basis of our physiological principles 

 is rendered broader and deeper, in proportion as our survey 

 of living beings is more extensive. The varieties of orga- 

 nization supply, in the investigation of each function, the 

 most important aids of analogy, comparison, contrast, and 

 various combination; and the nature of the process re- 

 ceives, at each step, fresh elucidation. These enlarged 

 views, which unfold to us the natural play of the animal 

 mechanism, are our surest guide in the study of its de- 

 ranged motions, an essential criterion for estimating the 

 nature and degree of the deviation, and an important indi- 

 cation of the means by which it may be corrected. Thus 

 general anatomy and physiology furnish the principles by 

 which we are guided in our attempts to preserve health, to 



