Volume 1

A textbook of human physiology / / translated from [the] 7th German edition by William Stirling.

  • Landois, Leonard
Date:
1891
Catalogue details

Licence: Public Domain Mark

Credit: A textbook of human physiology / / translated from [the] 7th German edition by William Stirling. Source: Wellcome Collection.

Provider: This material has been provided by Royal College of Physicians, London. The original may be consulted at Royal College of Physicians, London.

    592/602 (page 552)
    on^SSd^ P8 W«™ —™l the lubes capillaries, ft is ,,„',, , ,,' „ J' a? mmnded by a rich network of Bbhrig made experiments unon , , , ' i ?lv.e8°fi* 8Dlal] a™ °* N or'ammonia. the .mount .ol-C ...a, d H9< ' N ,'• « ! ''', ' ^ fc° him> digestion, increased to^tS^f«S3?^- ?,ai d''V y vallatioils ! {t « increased by b impeding the EE £ ' n'^'f' the application of cutaneous stimuli, and laritv of certain HKaS;& <i e*c™age ol gases also depends upon the men- muuUVf'!^ C,,taM0U' adoption of 0 also defends upon the yields § of the total amount of CO, exited! S^^TOS^&^iHs these animals it w a more important respiratory organ than the hZtH™ ' ' Suppression of the cutaneous activity by vanishing or dipping hf skinTn oil causes death bv asphyxia (frogs) sooner than ligature of the lungs does. Varnishing the Sk n 1\V n the ski? bIZTSI '5S? ,S C°VereS Witb a imi'C,'niea ble varmshtsuch as St,L^f^K^rW8 &fte* a ^.'J'^ly owing to the loss of too much heat J-ne loiination of crystalline ammonio-magnesic phospliate in the cutaneous tissue of such animals {Mcnhmzcn) is not sufficient to account for death, nor are congestion of i ternnl o.-a SJST tl '°nS. Sati8,'f t0,7 explanations. The retention of the volatile swhstS (S) present m the sweat is not sufficient. Strong animals live longer than feeble ones • horses die after several days [Qerlach) ; they shiver andlose flesh. The larger the cutaneo us'sml.ee left unvarnished the later does death take place. Rabbits die when f of their suriace^wSed. W hen the entire surface of the animal is varnished, the temperature rapidly falls (to 19°) the pulse and respirations vary ; usually they fall when the varnishing process is limited ; increased frequency of respiration has been observed (§ 225). Pigs, dogs, horses, when one-half of the body is varnished, exhibit only a temporary fall of the temperature and show signs of weak- ness, but do not die {EUenberger and Hofmeister). [In extensive burns of the skin not only is there disintegration of the coloured blood-corpuscles (v. Lesser), but in some cases ulcers occur in the duodenum. The cause of the ulceration, however, has not been ascertained satis- factorily {Curling).'] 2. Sebaceous Secretion.—The fatty matter as it is excreted from the acini of the sebaceous glands is fluid, but even within the excretory duct of the gland it stagnates and forms a white fat-like mass, which may sometimes be expressed (at the side of the nose) as a worm-like white body, the so-called comedo. The sebaceous matter keeps the skin supple, and prevents the hair from becoming too dry. Microscopically, the secretion is seen to contain innumerable fatty granules, a few gland-cells filled with fat, visible after the addition of caustic soda, crystals of cholesterin. and in some men a microscopic mite-like animal (Demodex folli- culorum). [Formation of Sebum.—The cells lining the acini of the glands proliferate and push the older cells towards the centre of the alveoli, where they undergo a fatty transformation to form the sebum. Thus the shed cells are themselves bodily transformed into sebaceous matter, a condition different to that obtaining in most of the other secretory glands.] Chemical Composition of Sebum.—The constituents are for the most part fatty ; chiefly olein (fluid) and palmitin (solid) fat, soaps, and some cholesterin ; a small amount of albumin and unknown extractives. Amongst the inorganic constituents, the insoluble earthy phosphates are most abundant ; while the alkaline chlorides and phosphates are less abundant. The vernixcaseosa, which covers the skin of a new-born child, is a greasy mixture of seba- ceous matter and macerated epidermal cells (containing 47'5 per cent. fat). A similar product is the smegma praeputialis (52 8 per cent, fat), in which an ammonia soap is present. The cerumen or ear-wax is a mixture of the secretions of the ceruminous glands of the ear (similar in structure to the sweat-glands) and the sebaceous glands of the auditory canal. Besides the constituents of sebum, it contains yellow or brownish particles, a bitter yellow extractive substance derived from the ceruminous glands, potash soaps, and a special fat The secretion of the Meibomian glands is sebum. [Lanoline.—Liebreich finds in feathers, hairs, wool, and keratin-tissues generally, o choles- terin fat, which however is not a true fat, although it saponifies, but an ethereal compound of certain fatty acids with cholesterin. In commerce it is obtained from wool, and is known by the above name ; it forms an admirable basis for ointments, and it is very readily absorbed by the skin.] Thus, the fat-like substance for protecting the epidermis is partly formed along with keratin in the epidermis itself. 3. The Sweat.—The sweat is secreted in the coil of the sweat-glands. At the