Page:Proceedings of the Royal Society of London Vol 1.djvu/409

Rh at the end of two hours it had fallen 14° in the thorax; and at the end of the experiment 20° in the thorax.

At the beginning of this experiment the ureters had been tied; and at the end of the experiment it was found that no urine was collected above the ligature.

The third experiment was made upon a rabbit; and the artiﬁcial respiration was continued one hour and forty minutes. A thermometer in the cavity of the abdomen fell in the ﬁrst hour from 100° to 89°; and in the next forty minutes to 85°; but in the cavity of the thorax it was as low as 82°.

Since the blood in these experiments was observed to retain its ﬂorid red colour in the arteries, it might be expected, according to the common theory of animal heat, to retain also its proper temperature; but Mr. Brodie observes, that this must also depend on the fulness and frequency of the pulse, together with the fulness and frequency of inspiration. It therefore became neceﬁary to attend particularly to these circumstances.

In the fourth experiment, which was also made upon a rabbit, the natural inspirations were imitated as nearly as possible; and at the end of forty minutes the pulse was found to continue as high as 140 in a minute, but the heat had declined from 99° to 92%. At the end of one hour and twenty-ﬁve minutes, a thermometer in the pericar- dium was 85°, in the abdomen 87°.

In the ﬁfth experiment the pulse continued at 140 for upwards of an hour, but the heat in the rectum declined from 101% to 92°.

A In a subsequent experiment two rabbits were chosen, as nearly alike in size and every particular as possible. Both were killed; but one was suffered to cool gradually without interruption; and in the other the circulation was continued by means of artiﬁcial rcspiration. At the beginning of the experiment the temperature of each was 99°.

At the end of half an hour that of the former was 99° ; the latter 97° Three quarters of an hour. . . . . . . . . . . . . . . . 98 95-; 'One hour. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 96% 94 Onehourandahalf. . . . . . . . ... . . . . . . . . . .. 94 91

It appeared, therefore, that respiration tended rather to cool than to support the animal heat. But since it was possible that a small portion of heat might be generated, but counteracted by the contact of cold air, a subsequent experiment was made, in which the large vessels of the heart were tied, so as to prevent any circulation of the blood; and in this case the heat remained comparatively greater than in the former, as the cooling effect of the air was not diffused to distant parts of the body.

From the whole the author concludes,

1st. That the inﬂuence of the brain is not directly necessary to the action of the heart.

2nd. That the interruption of the circulation is owing to the stoppage of respiration.