Elements of human physiology / by L. Hermann ; translated from the sixth edition by Arthur Gamgee.

  • Gamgee Arthur, 1841-1909.
Date:
1878
Catalogue details

Licence: Public Domain Mark

Credit: Elements of human physiology / by L. Hermann ; translated from the sixth edition by Arthur Gamgee. 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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    Pivtagon [Is a glucoside of lecithin (Liebreich), which occurs as the chief proximate constituent of the brain; it is probably also present in those liquids and solids of the body which yield lecithin. Unlike lecithin, it can readily and uniformly be crystallized, separating from its solutions in hot alcohol (when these are allowed to cool gradually) in the form of needles, which are usually ar- ranged in tufts or balls. It has approximately the following per- centage composition :—C 67-21, H 11-59, N 2-70, P 1-50, 0 17-0. When protagon is boiled with an aqueous solution of barium hydrate, it yields the products of decomposition of lecithin; but, in addition, a nitrogenous body, which appears to be identical with a siTbstance called cerebrin (Miiller), to which the formula Cj^HagNOg has been ascribed; the latter body is a glucoside, furnishing when boiled with dilute acids considerable quantities of a sweet body which reduces solution of cupric salts, but which is not ferment- able. The existence of protagon has been called in question (Dia- konow, Hoppe-Seyler), it being alleged that protagon is an inde- finite mixture of cerebrin and lecithin.] 2. Anhydrides of Sugar. Certain substances occur very widely diffused throughout the vegetable kingdom which, when subjected to hydrolytic influences, combine with water and form sugar; their close relationship to the sugars, and the fact that, like them, they contain H and 0 in the proportion in which these elements exist in water, places them amongst the carhohydrates, in a group which, after the name of one of its most prominent members, may be termed the group of the amyloses or starches. From their combining with water to form sugar, they may be considered to be anhydrides of sugar. The most characteristic bodies of this group are— Gum OjoHjqOu Starch 0«H,„0, Cellulose O^K^Jd^, Dextrin OgHmOs The formulae of these bodies, which appear to bear the same relation to the sugars as the ethers bear to the alcohols, are pro- bably multiples of the above, their ' conversion' into sugar being also in reality a process of decomposition. It appears likely that milk sugar, which, under hydrolytic in- fluences, is changed into a sugar analogous to dextrose—viz. gal- actose—is an ether of the latter body. Cane-sugar probably bears a somewhat similar relation to dextrose and levulose. Another class of sugar derivatives exists widely diffused in the D