Observations on the movements of the heart of the copper-head snake (Hoplocephalus superbus, Günth.) in and out of the body / by D. McAlpine.

  • McAlpine, Daniel, 1848-1932.
Date:
1890
Catalogue details

Licence: Public Domain Mark

Credit: Observations on the movements of the heart of the copper-head snake (Hoplocephalus superbus, Günth.) in and out of the body / by D. McAlpine. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    was now recorded, or 81 in 10 minutes, ranging from as low as 5 beats per minute, when there were relatively long pauses, up to 11 in a minute. The movement was less regular without, than with the pericardium, and this is in keeping with what we know of the steadying action of the pericardium and its contained fluid. The heart was next excised about 6 hours after death (exactly at 8.39 p.m., or S-i minutes after the body was opened up). The auricles alone contracted for the first minute, then the ventricle began, but at a much slower rate than the auricles. Hence the ventricle and auricles did not contract in unison, but independently. The ventricle contracted at first at an average rate of 4^ times per minute, or 22 times in 5 minutes, while the auricles in the succeeding 5 minutes contracted 92 times, or on an avei-age of 18| times per minute. During the same period, the ventricle onlj' contracted 18 times, or about one-fifth as often. The ventricle gradually began to beat at distant intervals, sometimes even of ten minutes, and finally ended with three beats at intervals of 1, ],and | minutes respectively. The ventricular contraction entirely'' ceased 23^ minutes after excision. Meanwhile, the two auricles continued to beat as near as may be together, but the left auricle ceased about the same time as the ventricle. The right auricle still continued beating steadily at a rate of 8 beats per minute, then it gradually became enfeebled, and ceased to beat about 35 minutes after the left auricle. Thus the ventricle and left auricle beat for about 6^ hours after somatic death, and the right auricle for about 7 hours, and almost exactly one hour after excision of the heart. For purposes of comparison, however, we will reckon the excised heart as a whole, and the pulsations would then cease with the ventricle, or 23i minutes after excision. Both ventricle and auricles reacted to stimulation, such as the prick of a pin after spontaneous beating had ceased. The ventricle was found to do so for over 45 minutes, and the right auricle for about 15 minutes. The temperature of the room was pretty constant throughout at 19° C, and the heart was simply laid out on a moistened plate. The second and much smaller snake, measuring only IG inches, was killed Avith chloroform. Tlie efiect of _ the chloroform was, that the snake coiled itself up and remained perfectly motionless, all but the tip of the tail. This moved to and fro for about 10 minutes, then quivered only,