A Text-book of physiological chemistry / Olof Hammarsten.

  • Hammarsten, Olof, 1841-1932.
Date:
1908
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Licence: Public Domain Mark

Credit: A Text-book of physiological chemistry / Olof Hammarsten. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    in the plant chiefly those of reduction and synthesis have thus far Ijeen studied. WoHLER 1 in 1824 was the first to observe an example of synthetical PROCESSES within the animal organism. He showed that when benzoic acid is introduced into the stomach it reappears as hippuric acid in the urine, after combining with glycocoU (aminoacetic acid). Since the discovery of this synthesis, which may be expressed by the following equation: CeHs.COOH + NH2.CH2.COOH = NH (C6H5.CO).CH2.COOH +H2O, Benzoic acid GlycocoU Hippuric acid and which is ordinarily considered as a type of an entire series of syntheses occurring in the body where water is eliminated, the number of known syntheses in the animal kingdom has increased considerably. ]\Iany of these syntheses have also been artificially produced outside of the organism, and numerous examples of animal syntheses of which the course is abso- lutely clear will be found in the following pages. Besides these well-studied syntheses, there occur in the animal body also similar processes unquestion- ably of the greatest importance to animal life, but of which we know nothing with positiveness. We enumerate as examples of this kind of synthesis the re-formation of the red-blood pigment (the haemoglobin), the formation of the different proteins from simpler substances, and the produc- tion of fat from carbohydrates. This last-mentioned process, the formation of fat from carbohydrates, is also an example of reduction processes which occur to a considerable extent in the animal body. Formerly the view was generally accepted that animal oxidation takes place in the fluids, while to-day we are of the opinion, derived from the investigations of Pfluger and his pupils,^ that it is connected with the form-elements and the tissues. The question as to how this oxidation in the form-elements is induced and how it proceeds cannot be answered with certainty. When a substance is oxidized by neutral oxygen at the ordinar\' tempera- ture or at the temperature of the body, the substance is said to be easily oxidized or autooxidized, and the process is considered as a direct oxidation or auto- oxidation. As the oxygen of the inspired air, and that of the blood, is neutral molecular oxygen, the old assumption that ozone occurs in the organism has now been discarded for several reasons. On the other hand, the chief groups of organic nutritives, carbohydrates, fat, and proteins, the last two forming • the chief mass of the animal body, are not autooxidizable substances. They are on the contrary bradoxidizable (Traube) or dysoxidizable bodies. ' Berzelius, Lehrb. d. Chemie, ubersetzt von Wohler, 4, p. 356, Abt. 1, Dresden, 1831. ^ Pfluger, Pfliiger's Archiv. 6 and 10; Finkler, ibid., 10 and 14; Oertmann, itid.t 14 and 15; Hoppe-Seyler, ibid., 7.