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 seventh German edition with additions by William Stirling.

Landois, L. (Leonard), 1837-1902. Lehrbuch der Physiologie des Menschen. English

Date:: 1891

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 seventh German edition with additions by William Stirling. Source: Wellcome Collection.

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$same time the nuclei of the secretory cells Ijecome more spherical and the cells (horse) become more grannlar. As long as the secretion is small in amount, the water secreted is evaporated at once from the skin along with the volatile con- stituents of sweat; as soon, however, as the secretion is increased, or evaporation is prevented, drops of sweat appear on the surface of the skin. The former is called insensible perspiration, and the latter sensible perspiration. [Broadly, the quantity is about 2 lbs. in twenty-four hours.] The sensible perspiration varies greatly ; as a rule, tlie right side of the body perspires more freely than the left. The palms of the hands secrete most, then follow the soles of the feet, cheeic, breast, upper arm, and fore-arm {Peiper). It falls from morning to inid-day, and rises again towards evening, reaching its maximum before midnight. Much moisture and cold in the surrounding atmosphere diminish it, and so does diuresis. In children, the insensible pei - spiration is relatively great. The drinking of water favours it, alcohol diminishes it {H. Schmid). Method. —Sweat is obtained from a man by placing him in a metallic vessel in a warm bath ; the sweat is rapidly secreted and collected in the vessel. In this way Favre collected 2560 grams of sweat in 1| hour [by exposing himself to a hot-air bath and drinking at the same time hot drinks]. An arm may be inclosed in a cylindrical vessel, which is fixed air-tight round the arm with an elastic bandage {Schottin). Amongst animals, the horse sweats, so does the ox, but to a less extent ; the vola and planta of apes, cats, and the hedgehog secrete sweat; the snout of the pig sweats (?), while the goat, rabbit, rat, mouse, and dog are said not to sweat {Luchsinger). [The skin over the body and the pad on the dog's foot contain numerous sweat-glands, which open free on the surface of the pad and into the hair-follicles on the general surface of the skin ( W. Stirling).} Microscopically.—The sweat contains only a few epidermal scales accidentally mixed with it, and fine fatty granules from the sebaceous glands. Chemical Composition of Sweat.—Its reaction is alkaline, although it fre- quently is acid, owing to the admixture of fatty acids from decomposed sebum. During profuse secretion it becomes neutral, and lastly alkahne again {Triimpy and Luchsinger). The sweat is colourless, slightly turbid, of a saltish taste, and has a characteristic odour varying in different parts of the body; the odour is due to the presence of volatile fatty acids [specific gravity, 1003-1005.] The con- stituents are water, which is increased l3y copious draughts of that fluid, and solids, which amount to 1-2 per cent. (O'TO to 2-66 per cent.—Funlie), and of these 0-90 per cent, is organic and 0-30 inorganic. Amongst the organic consti- tuents are neutral fats (palmitin, stearin), also present in the sweat of the palm of the hand, which contains no sebaceous glands, Cholesterin, volatile fatty acids (chiefly formic, acetic, butyric, propionic, caproic, capric acids), varying qualita- tively and quantitatively in difi'erent parts of the body. These acids are most abundant in the sweat first (acid) secreted. There are also traces of proteids (similar to casein) and a trace of albumin and urea, about O'l per cent. [Kast found sulphuric acid united as ethereal sulphate of skatol and phenol, also oxy- acids, and Capricana found kreatinin.] In ursemic conditions (anuria in cholera) urea has been found crystallised on the skin. When the secretion of sweat is greatly increased, the amount of urea in the urine is diminished, both in health and in ursemia {Leute). The nature of the reddish-yellow pigment, which is extracted from the residue of sweat by alcohol, and coloured green by oxalic acid, is unknown. Amongst inorganic constituents, those that are easily soluble are more abundant than those that are soluble with difficulty, in the proportion of 17 to 1 ; sodium chloride, 0-02 ; potassium chloride, 0-02; suliDhates, 0-01 per 1000, together with traces of earthy phosphates and sodium phosphate. [Moreover, the relative proportion of salts in sweat is quite, different from that in urine.] Gases. —Sweat contains COg in a state of absorption and some X. When decomposed with free access of air^ it yields ammonia salts {Gorup-Besanez). Excretion of Substances.—Some substances when introduced into the body reappear in the sweat—benzoic, cinnamic, tartaric, and succinic acids are readily excreted ; quinine and potassic iodide with more difficulty. Mercuric chloride, arsenious and arsenic acids, sodium and$