Oxidations and reductions in the animal body / by H.D. Dakin.

  • Dakin, H. D. (Henry Drysdale), 1880-1952
Date:
1912
Catalogue details

Licence: In copyright

Credit: Oxidations and reductions in the animal body / by H.D. Dakin. Source: Wellcome Collection.

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    I. INTRODUCTION. The evolution of heat as the result of vital activities and its cessation with death must have been obvious to man in the earliest stages of his development. It was recognized long ago that the phenomena of pro- duction of animal heat and the combustion of carbonaceous materials outside the body had much in common. The discovery of oxygen by Priestley and by Scheele (1771) first made it possible to form a rational conception of the chemical changes involved in combustion, but it was left for Lavoisier to clearly state the fundamental facts in a relatively modern form. The chemistry of the oxidations taking place in the animal body may fairly be said to date from the publication in 1780 of Lavoisier’s “ Experiences sur la respiration des animaux et sur les changements qui arrivent a l’air en passant par leur poumon ”. It was clearly shown by Lavoisier that oxygen was taken up by the lungs and in part converted into carbon dioxide, the carbon in Lavoisier’s opinion being derived from the blood. The whole process was recognized as one of combustion and was believed to constitute the natural mechan- ism for the supply of animal heat. The necessity of furnishing the body with combustible material in the form of food in order to avoid injurious loss of body substance was clearly understood as was also the increased output of carbon dioxide following muscular activity. Perhaps one of the most interesting results of Lavoisier’s investiga- tions is the fact that they led him to the conviction that vital processes are made up of a series of chemical reactions (1792). Unfortunately this idea was not revived until a much later date, and not until Liebig emphasized the importance for biology of the newly developing organic chemistry were material advances made. By degrees a clearer know- ledge was obtained of the chemical nature of the fats, carbohydrates and proteins and of the laws governing their mutual interconversions in the body. One of the most important methods devised for the in- vestigation of the metabolic activities of living organisms consists in the study of so-called “balances” in which the intake and output of carbonaceous and nitrogenous substances are compared. Methods for 1