Volume 1

A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the fifth German edition with additions by William Stirling.

  • Landois, L. (Leonard), 1837-1902.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of human physiology : including histology and microscopical anatomy with special reference to the requirements of practical medicine / by L. Landois ; translated from the fifth German edition with additions by William Stirling. Source: Wellcome Collection.

    578/628
    its activity is coupled with the vitality of the cells of the yeast. If yeast be boiled, or if it he mixed with carbolic or salicylic acid, or chloroform, all of which destroy its activity, it cannot produce the alcoholic fermentation. As yet no one has succeeded in extracting from yeast a substance which will excite the alcoholic fermentation. All the organised ferments grow and multiply during their activity at the expense of the substances in which they occur. Thus the alcoholic fermenta¬ tion depends upon the “ life ” of the yeast. They are said to be killed by oxygen subjected to the compression of many atmospheres (P. Bert). But it is important to note that Hoppe-Seyler has extracted from dead yeast (killed by ether), an unorganised ferment which can change cane-sugar into grape-sugar.] 10. Haemoglobin, the colouring matter of blood, which, in addition to C, H, 0, N, and S, contains iron, may be taken with the albuminoids (§ 11). (3) Glucosides containing Nitrogen. In addition to chondrin, the following glucosides containing nitrogen, when sub¬ jected to hydrolytic processes, may combine with water, and form sugar and other substances :— Cerebrin (§ 322) = (Geoghegan). Protagon—C 66#29, H 10'69, N 2 ‘39, P 1’068, per cent.—occurs in nerves, and contains phosphorus (§ 322). Chitin, 2(CigH26N2O10), is a glucoside containing nitrogen, and occurs in the cutaneous coverings of arthropoda, and also in their intestine and tracheae ; it is soluble in concentrated acids, e.g., hydrochloric or nitric acid, but insoluble in other reagents. According to Sandwick, chitin is an amin-derivative of a carbohydrate with the general formula n(C12H20O10). The hyalin of worms is closely related to chitin. (Solanin, amygdalin (§ 202), and salicin, &c., are glucosides of the vegetable kingdom). (4) Colouring Matters containing Nitrogen. Their constitution is unknown, and they occur only in animals. They are in all probability derivatives of hsemoglobin. They are—(1) heematin (§ 18, A), myohsematin (§ 232. § 292, a), and haematoidin (§ 20). (2) Bile-pigments (§ 177, 3). (3) Urine-pigments (except Indican). (4) Melanin—C 44% H 3, N 9‘9, O 42'6—or the black pigment, which occurs partly in epithelium (choroid, retina, iris, and in the deep layers of epidermis in coloured races) and partly in connective-tissue corpuscles (Lamina fusca of the choroid). II. Organic Acids free from Nitrogen. (1) The fatty acids, with the formula CnH2n.10(OH), occur in the body partly free and partly in combination. Free volatile fatty acids occur in decomposing cutaneous secretions (sweat). In combination, acetic acid and caproic acid occur as amido-compounds in glycin ( = amido-acetic acid), and leucin (= amido-caproic acid). More especially do they occur united with glycerine to form neutral fats, from which the fatty acid is again set free by pancreatic digestion (§ 170, III). (2) The acids of the acrylic acid series, with the formula CnH2„.30(H0), are represented in the body by one acid, oleic acid, which in combination with glycerine yields the neutral fat olein. 251. Fats. (1) Neutral fats occur very abundantly in animals, but they also occur in all plants ; in the latter more especially in the seeds (nuts, almonds, cocoa nut, poppy), more rarely in the pericarp (olive) or in the root. They are obtained by pressure, melting, or by extracting them with ether or boiling alcohol. They \e.g., tristearin, C57Hn0O6] contain much less O than the carbohydrates, such as sugar and starch ; they give a greasy spot on paper, and when shaken with colloid substances, such as albumin, they yield an emulsion. When treated with superheated steam, or with