Page:Proceedings of the Royal Society of London Vol 2.djvu/42

Rh of the brain, yet may be influenced through the brain, the office of which is considered as purely sensorial. The separate existence of these powers is illustrated by a review of the various classes of animals, in the lowest of which we find only the muscular system; in the next above the muscular and nervous without sensorium; and in the most perfect animals we find the three vital powers combined, each having existence not immediately depending on the others, but so connected that no one can subsist long without the others, since all are supported by the same circulation, that is dependent for its continuance upon muscular action, which cannot exist without respiration, while this again depends on the nervous system for its continuance.

Although the heart of a frog retains its power long after the brain and spinal marrow are removed, nevertheless Dr. Philip found that its force may be for a time extremely impaired, by suddenly crushing the brain or spinal marrow, but it will again recover its power after the entire destruction of those parts; and corresponding effects were observed, though not so distinctly, in rabbits.

It is to this cause that the author ascribes the difference between his results and some of those of M. Le Gallois, who, instead of employing a small wire to destroy the spinal marrow, used an instrument which fitted the cavity of the spine, and consequently crushed the marrow more suddenly.

From the whole of his experiments the author concludes, that the involuntary muscles obey the same laws as those of voluntary motion; that the difference arises from their being under different stimuli; that both are liable to be stimulated through the nervous system; that they each have power independent of that system. That what has been called nervous system consists of two parts, one purely sensorial, the other conveying impressions.

That the three powers are combined in the most perfect animals. That the muscular may be destroyed through the nervous system, and the nervous through the sensorial; and though each is not strictly dependent on the others, they are so connected that no one can exist long without the others. 



These experiments were undertaken by the author, in order to ascertain the truth or fallacy of M. Le Gallois' conclusion respecting the action of the heart being dependent on the spinal marrow. For since the death of quadrupeds (on which M. Le Gallois operated) is so readily produced by injury to the vital organs, it appeared to Mr. Clift that fishes would be far preferable, from their being more tenacious of life.

After two or three preliminary experiments on the duration of the