ON THE STUDY OF PHYSIOLOGY. 79 



animal kingdom leads to what may be called ' general ana- 

 tomy/ the basis of general physiology ; the objects of which 

 are to determine the organization, and unfold the vital laws 

 of the whole system of living beings. 



In the physical sciences we have the power of insulating 

 the various objects of our research ; of analysing them 

 into their component elements, of subtracting these succes- 

 sively, and thus determining beforehand all the conditions 

 of the problem we may be studying. It would be desirable 

 to employ the same proceeding in natural history ; and it is 

 resorted to, when the objects are sufficiently simple : but 

 they are for the most part too complicated, and connected 

 two closely by mutual influences. We cannot analyse an 

 animal of the higher orders, and observe the simple result 

 of each organ by itself ; for if we destroy one part, the mo- 

 tion of the whole machine is stopped. The phenomena 

 come before us under conditions not regulated by our own 

 choice, and in a state of complication requiring close atten- 

 tion and careful discrimination to search out and determine 

 the precise share of each component part. 



In this difficulty, comparative observations afford some 

 assistance. The animals of inferior classes are so many sub- 

 jects of experiment ready prepared for us; where any organ 

 may be observed under every variety of simplicity and com- 

 plication in its own structure — of existence alone, or in com- 

 bination with others. 



