Page:Proceedings of the Royal Society of London Vol 1.djvu/459

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In some former experiments it was found, that in an animal from whom the head was removed, the circulation of the blood might be maintained by means of artiﬁcial respiration; that under these circumstances the blood underwent the usual changes of colour in the tan capillary systems, and carbonic acid was evolved from the lungs, but no heat was generated, and the animal cooled more rapidly than a dead animal of the same size. In the present communication, some experiments are detailed, which were instituted with a view to the further elucidation of this subject.

An apparatus was constructed for the purpose of measuring the air consumed in respiration; and two series of experiments were instituted,—the ﬁrst to ascertain the quantity of air consumed by animals breathing under ordinary circumstances; and the second to ascertain the quantity consumed by animals which are made to breathe artiﬁcially after the functions of the brain are destroyed. It was found, that in animals breathing under these different circumstances, there is little or no difference in the quantity of oxygen which diappears, and of carbonic acid, which is evolved in a given space of time; but that it uniformly happens, that Where the functions of the brain are suspended, no heat is generated; and that the animal cools more rapidly than a dead animal.

In another experiment, an animal apparently dead from the poison of essential oil of almonds, was made to recover, by respiration being artiﬁcially produced until the poison had ceased to exert its inﬂuence. It was found, that while the functions of the brain were suspended, no heat was generated, but that as the sensibility of the animal was restored, the power of generating heat returned.

These experiments, as well as those detailed in the Croonian Lecture for 1810, go far towards proving that the temperature of warm- blooded animals is considerably under the inﬂuence of the nervous system; but, what is the nature of the connexion betwecn them. Whether the brain is directly or indirectly necessary to the generation of animal heat .3 These are questions which, in the present state of our knowledge, must remain unresolved.

Since the solvent glands in birds are larger than in quadrupeds, Mr. Home has investigated their structure in different classes of birds, and has here collected several varieties that he has observed;