Treatise on human physiology : For the use of students & practitioners of medicine / By Henry C. Chapman. Illustrated with 595 engravings.

  • Chapman, Henry C. (Henry Cadwalader), 1845-1909.
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: Treatise on human physiology : For the use of students & practitioners of medicine / By Henry C. Chapman. Illustrated with 595 engravings. 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.

    70/934 (page 64)
    acid, phospliorized substances, which, according as they do or do not yield xanthin, are called nucleins or paranucleins. Nuclein occurs as nucleo-histon in the leucocytes of the blood and as the chief constituent of cell nuclei, parauucleiu in casein, yitellin, etc. The supposed importance attached to nucleo-histon as a factor iu the production of the coagulation of the blood will be considered hereafter. Albuminoids.—The substances embraced together as the third class of protein bodies differ so among thcmselyes that they cannot be regarded as a natural group. The albuminoids agree, howeyer, in constituting important parts of the skeleton and being found generally in the economy in an insoluble state and in resisting the action of reagents, particularly of those which dissolye albumins. The albuminoids are deriyed in the economy from the proteids, but do not appear to be couyertible into the latter. Keratin.—This substance is the chief constituent of epidermis, hair, and nails, and in the modified form of neuro-keratiu is found in the brain and the medullary sheath of nerves. As found in the hair keratin consists of carbon, hydrogen, nitrogen, oxygen, and sulphur, being yery rich in the latter. Part of the sulphur, at least, appears to be in a loose state of combination, lead combs becoming black l)v long usage through formation of lead sulphide. Elastin.—This albuminoid is found in the connective tissues and in some cases, as in the ligamentum nuchte, to such an extent as to constitute a special tissue. The elastic tissue in the ligamentum nuchse of the giraffe and elephant is much developed. The liga- mentum nuchffi in the giraffe dissected by the author measured in situ more than 9 feet, 6 feet of which, after removal from the body, contracted to 4 feet. Elastin differs chemically from keratin in containing very little, if any, sulphur. Elastin is very insoluble in boiling water and in most reagents. Collagen.—This substance is the principal constituent of the con- nective tissues and as ossein of the organic substance of bone. It is found also in cartilage, more or less mixed with the substances constituting its chemical basis, the so-called chondrigen. Collagen can be obtained from bones by treating the latter mth hydrochloric acid, which dissolves the earthy matters, and then removing the acid with water. Collagen consists chemicallv, according to Hof- mcister,' of C 50.75, H (5.47, X 17.86, S +'0 24.92. It is in- soluble in water, salt solutions, dilute acids, and alkalies, and is converted by continuous boiling into gelatine. It will be remem- bered that, in addition to the protein bodies just considered, a num- ber of other nitrogenous principles are found in the human economy that cannot be placed in the above category. To the consideration of these let us now turn, premising, however, that, as most of them will be considered again more or less in detail, a passing notice will suffice in tliis connection.