THE NERVOUS SYSTEM.
Sir 13. Brodie demonstrated by a series of the most ingeniously conceived and happily executed experiments, that when animals were decapitated and respiration was kept up by artificial means, so that the blood circulated as usual, and the process of change from the venous to the arterial state went on uninter ruptedly, the ordinary quantity of carbonic acid being eliminated, all the while, that, ne vertheless, the temperature fell rapidly, even more rapidly than when no artificial respiration was maintained.
Dr. Chossat completed these researches upon the nervous system in its relations with the production of heat, by demonstrating in a series of experiments the following very im portant fact, viz. that the depression of animal heat is constantly in relation with lesions of the nervous system, whether these lesions im plicate the cerebro-spinol system, or the system of the great sympathetic.
We necessarily confine ourselves, in alluding to these admirable researches, to the most general results, and the conclusions flowing most immediately from the experiments insti tuted. We reserve a more particular mention
of them for the proper place, namely, the article on RESPIRATION, to which we beg to refer. With regard to the opinions of writers generally, we shall be content to observe here, that they have fur the most partr ed the single physiological condition whir the subject of their particular study as the only source of animal heat. The general result of their united labours, however, is, that there are two principal sources, the one depending on the arterial blood, the other on the energy of the nervous system,—a conclusion to which we have come by another way, by combining all the known facts that bear upon animal heat, and embracing the manifestations presented by the whole of the animal kingdom as well as the isolated phenomena exhibited by man, and this not in one but in every condition of ex istence, not only in the state of health but of disease likewise, not as beings independent of all things around them, but as living in intimate relationship with external agents.