8thly, The preceding essays were made upon warm and red-blooded animals. Similar attempts were repeated on cold and red-blooded animals, but with no effect.
9thly, The nerves which immediately supply the gastric organs of the frog, are so delicate as to make it an extremely difficult matter to get them into proper contact with the zinc: a small contraction of the stomach was, however, obtained by Jadelot on operating directly on these nerves; but this contraction was similar, no doubt, to those which I have so frequently observed in other experiments, and not to be compared to the astonishing effects which are observable in the voluntary muscles. I shall conclude, therefore, that with respect to the galvanic phenomena, there exists a wide difference between the muscles of the animal life and those of the organic life.
I have now collected proof enough, I trust, for resolving, with certainty, the question proposed in the above chapter, and for establishing it as a fundamental principle.—1st, That the brain does not directly influence the organs and the functions of the internal life; and 2dly, That, therefore, the interruption of these functions, in case of any great lesion of the brain, is not an immediate effect of such lesion.
Nevertheless, I am far from considering the cerebral action as foreign entirely to the organic life. I only maintain that its influence upon it is indirect, and as yet but little known. I have been somewhat prolix upon this subject; for certainly nothing in medicine is more vague than the sense which is commonly attached to the words nervous action, cerebral action, &c. There is never a proper distinction made between that which belongs to one life, and that which is the attribute of the other. Cullen, in particular, may be reproached with having exaggerated the influence of the brain.
II. Is the interruption of the functions of the organic life, the indirect effect of the cessation of the cerebral action?
The organic life continues to subsist for a certain time, after the apparent death of the individual. There must be some intermediate agents then, the cessation of the action of which, occasions the death of the inward organs. Such agents are chiefly the mechanical organs of respiration. The series of the phenomena are the following:
1st, The cerebral actions are interrupted.—2dly, The mechanical functions of the lungs are put an end to.—3dly, There is an annihilation of their chemical functions.—4thly, The black blood circulates in all the parts.—5thly, The movement of the heart and the action of all the parts is weakened.—6thly, Suspended.
All the inward organs then, die nearly as they do in asphyxia; that is to say—1st, Because they are penetrated by the black blood.—2dly, Because the circulation ceases to communicate that motion which is essential to their life.