On the influence of physical agents on life / by W.F. Edwards ; translated from the French, by Dr. Hodgkin and Dr. Fisher.

Date:
1832
Catalogue details

Licence: Public Domain Mark

Credit: On the influence of physical agents on life / by W.F. Edwards ; translated from the French, by Dr. Hodgkin and Dr. Fisher. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    makes a demand in that direction, and the last additional demand is made as the period of puberty takes place by the development of the sexual organs. The habits and passions of the young animal concur with its organization to give the external character to its circulation, whilst those of the adult concur with the or- ganic changes which it has undergone, in producing the preponderance of the internal circulation. It is to these differences, which I have briefly sketched, that Dr. Holland refers the inferior power which the young, compared with the adult animal, possesses, of resisting cold. When cold has constringed the vessels of the surface, a larger quantity of blood is thrown upon the internal organs, which receive it, with a less proportionate capacity of vessels, than in the adult. The proportion which the blood in the lungs bears to the inspired air is increased, and the production of heat, according to the Doctor's hypothesis, is diminished as a consequence. Adult animals in summer have a circulation of a more external and juvenile character than in winter; hence their power of producing heat is liable to a similar reduction by the application of cold. Dr. Holland brings for- ward several interesting facts, and employs considerable ingenuity of reasoning to support of his views, and to exhibit the importance of their application ; they do not, however, appear to contain the whole truth. Why does the vigorous adult maintain the ruddy colour of his well-injected skin in a temperature, in which the infant would be pale and benumbed with cold! Dr. Holland himself remarks, that the greater vigour of the adult enables him to resist cold better than the in- fant. The reader is left to form his own opinion of what this vigour consists, and I confess, that I think this is to be found in the different condition of the nervous system, which Dr. Holland appears not to take into account in his investigation of the calorific process. I must return to his objection to Dr. Edwards's view regarding the produc- tion of heat, when we shall have to consider the changes of the air effected by respiration. [The following experiments, which the kindness of Sir Astley Cooper has allowed me to extract from amongst several re- corded in one of his Memorandum Books, dated 1790, anti- cipate and corroborate some of the observations of Dr. Ed- wards. — They have not to my knowledge been hitherto pub- lished.'] Experiment I A young puppy was immersed in warm water, at about 120° Fahr. for one minute and a half. It struggled violently, and during the latter part of-this time threw out the air from its lungs. It then remained still for another minute and a half, when its struggles were renewed, at which time it voided its excrement. These efforts were soon over. After remaining still for three minutes, it was put into another vessel containing water of the same tem- perature. In this it gasped twice or thrice. In ten minutes after its first immer- sion I opened it — a slight undulation was observable at the lower part of the