Medicine. 243 



the animal economy, notwithstanding all the dili- 

 gence and ingenuity bestowed on them by a mul- 

 titude of physiologists, have not been cultivated 

 with equal success, and indeed can scarcely be 

 said to be better understood at this time than they 

 were at the close of the seventeenth century. 



The celebrated doctrine of the Vitaliti/ of the 

 blood, which was first distinctly taught in modern 

 times by Harvey, found a new and able advo- 

 cate in Mr. John Hunter, who maintained, in 

 his lectures, that the fluids as well as the solids 

 were .possessed of the principle of life. The argu- 

 ments by which he endeavoured to support this 

 doctrine are not only ingenious and forcible in 

 themselves; but they derive additional strength 

 from the theory of respiration, and the principles 

 of pneumatic chemistry, which are now generally 

 received. 



Within the period assigned to this retrospect, 

 the functions and laws of the Nervous System have 

 been investigated with the greatest zeal. Willis, 

 in the seventeenth century, had laid the foundation 

 of this improvement, by his accurate description 

 of the brain and nerves. Vieussens, in his Neu- 

 rographia, pursued the subject with much discern- 

 ment. Early in the eighteenth century Hoffman 

 still further prosecuted this inquiry; and at a 

 more advanced period of it. Dr. Cullen exerted 

 all his powers in the same course. The use made 

 by the two latter of the knowledge gained on this 

 subject, in constructing their medical theories, 

 will be mentioned more particularly under the 

 succeeding head. 



Comparative physiology has been cultivated with 

 great ardour and success in the course of the cen- 

 tury now under contemplation. Haller, though 

 chiefly devoted to human physiology, did not negr 

 lect the instruction which may be derived from a. 



