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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    9f inches in length, and was killed with chlurofonn. Unlike the last, the mouth did not gape after death, but the sensitive tip of the tail trembled occasionally until the chloroform had taken fatal efiect. This specimen was only removed from the influence of the chloroform after 84- minutes, and -t minutes afterwards the heart was exposed. For about a minute no sign of movement was observed, then the beating commenced, and for 4 successive minutes the beats were 37, 46, 47, and 46 respectively. The pericardium was next removed as delicately as possible, and the beats fell to less than half the above, although only two minutes elapsed between the two records. The beating, however, was very regular, and for 8 successive minutes ga^'e 21 per minute. The heart was now excised, and the beating at first was rather irregiQar. Two minutes after the last record the beats were 20 per minute, and for 10 minutes in succession, 3C, 40, 15, 17, 25, 28, 30, 31, 32, and 33 respec- tively, or an average of about 29 beats per minute. During the first three minutes after excision, a very inteiesting phenomenon presented itself. The heart travelled along the moistened plate in the direction of its base, and thus ])rogression as well as pulsation exhibited itself. As I was always prepared for such a movement, the plate on which the heart was laid out had marks to indicate the slightest progress. The distance travelled happened to be the length of the heart itself, viz. -{^ inch, and the rate of progression j% inch the first miinite, ^ inch each the second and third minutes. There is something positively grotesque at first sight in an excised portion of the body, such as the heart, beating away and moving along at the same time, but I had become so familiar with this progressive movement in the excised heart of the frog, that it was to me not an unexpected occurrence. In the excised beating heart, there is an exhibition of energy which is merely a continuation of the habitual Avork of the organ, but in the excised moving heart, there is a display of power for which we are unprepared. Just as in the detached gill, labial palp, or foot of the mussel, we might expect ciliary motion to continue, but not necessarily the progressive movement which they exhibit. The cause of this progressive movement in the latter case is evident, being due to the cilia ; but how the excised heart is propelled, and why in tlie direction of base or apex, I leave to others