ON THE STUDY OF PHYSIOLOGY. G5 



but incontestable influences of otber parts, wlilch are usu- 

 ally denominated sympatbies. Tims, as tlie successive 

 undulations of water spread wider and wider as they recede 

 from the point first agitated, our chemical examination of a 

 single excretion, by virtue of the mutual influences which 

 bind together all parts of our system, expands at last to 

 considerations embracing the whole economy. 



For the theory of diabetes we are principally indebted to 

 chemistry ; and we ought not to omit acknowledging the 

 debt, because its amount has not been increased by the 

 suggestion of an adequate remedy. 



With these strong facts before our eyes, and with the 

 knowledge that nature, however sportively various in unes- 

 sential details, is generally uniform in the leading princi- 

 ples of the means by which she accomplishes similar pur- 

 poses, may we not reasonably expect that the action of 

 many remedies will be traced hereafter to chemical influ- 

 ence ? May we not hope that the dark corner of our science, 

 the modus operandi of its remedial administrations, will 

 receive light from this quarter ? 



It is, however, in most cases the result, and not the ope- 

 ration itself, that we learn from chemistry. By compar- 

 ing the blood and the urine, we estimate the office of the 

 kidney ; but we know just as little as we did before of that 

 wonderful and mysterious process, by which the capillaries 

 of the gland transform blood into urine ; and when we see 

 the capillaries of other parts convert this same blood into 

 twenty other fluids or solids, we feel still more forcibly the 

 striking contrast between these and the operations com- 

 monly called chemical, and the insufficiency of explana- 

 tions grounded merely on the analogies of the latter 

 changes. If a gland, a membrane, a muscle, or a bone, in 

 their operations of secretion and nutrition, be chemical in- 

 struments, their analogy to those employed in our labora- 

 tories is so remote, as to be hardly perceptible. 



Of the attempt at explaining the sentient and contrac- 

 tile operations of the nerves and muscles by chemical agen- 



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