CUTANEOUS ABSORPTION. 449 



8. Paridrosis or qualitative changes in the secretion of sweat, e.g., the rare case of "sweating 

 of blood " (haBmatohidrosis), is sometimes unilateral. According to Hebra, in some cases this 

 condition represents a vicarious form of menstruation. It is, however, usually one of many 

 phenomena of nervous affections. Bloody sweat sometimes occurs in yellow fever. Bile- 

 pigments have been found in the sweat in jaundice; blue sweat from indigo (Bizio), from 

 pyocyanin (the rare blue colouring-matter of pus), or from phosphate of the oxide of iron (Osc. 

 Kollmann) is extremely rare. Such coloured sweats are called chromidrosis. Numerous micro- 

 organisms (which, however, are innocuous) live between the epidermal scales and on the hairs, 

 two varieties of Saccharomycetes ; in cutaneous folds Leptothrix epidermalis, various Schizo- 

 mycetes, and five kinds of Micrococci ; and between the toes Bacterium graveoleus (Bordoni' 

 Uffreduzzi), which causes the odour of the sweat of the feet. Micro-organisms are also the 

 cause of yellow, blue, and red sweat ; the last is due to Micrococcus hsematodes. 



Grape-sugar occurs in the sweat in diabetes mellitus ; uric acid and cystin very rarely ; and 

 in the sweat of stinking feet, leucin, tyrosin, valerianic acid, and ammonia. Stinking sweat 

 (bromidrosis) is due to the decomposition of the sw r eat, from the presence of a special micro- 

 organism (Bacterium fcetidum Thin). In the sweating stage of ague butyrate of lime has been 

 found, while in the sticky sweat of acute articular rheumatism there is'more albumin (Anselmino), 

 and the same is the case in artificial sweating (Leube) ; lactic acid is present in the sweat in 

 puerperal fever. 



The sebaceous secretion is sometimes increased, constituting seborrhcea, which may be local 

 or general. It may be diminished (Asteatosis cutis). The sebaceous glands degenerate in old 

 people, and hence the glancing of the skin (Remy). If the ducts of the glands are occluded the 

 sebum accumulates. Sometimes the duct is occluded by black particles or ultramarine (Unna) 

 from the blue used in colouring the linen. When pressed out, the fatty worm-shaped secretion 

 is called "comedo." 



289. CUTANEOUS ABSORPTION GALVANIC CONDUCTION. After long immersion in 

 water the superficial layers of the epidermis become moist and swell up. The skin is unable to 

 absorb any substances, either salts or vegetable poisons, from watery solutions of these. This 

 is due to the fat normally present on the epidermis and in the pores of the skin. If the fat be 

 removed from the skin by alcohol, ether, or chloroform, absorption may occur in a few minutes 

 (Parisot). According to Rohrig, all volatile substances, e.g., carbolic acid and others, which 

 act upon and corrode the epidermis, are capable of absorption. "While according to Juhl, such 

 watery solutions as impinge on the skin, in a finely divided spray, are also capable of absorption, 

 which very probably takes place through the interstices of the epidermis. 



[Inunction. When ointments are rubbed into the skin so as to press the substance into the 

 pores, absorption occurs, e.g., potassium iodide in an ointment so rubbed in is absorbed, so is 

 mercurial ointment. V. Voit found globules of mercury between the layers of the epidermis, 

 and even in the chorium of a person who was executed, into whose skin mercurial ointment had 

 been previously rubbed. The mercury globules, in cases of mercurial inunction, pass into the 

 hair-follicles and ducts of the glands, where they are affected by the secretion of the glands and 

 transformed into a compound capable of absorption. An abraded or inflamed surface (e.g., after 

 a blister), where the epidermis is removed, absorbs very rapidly, just like the surface of a wound 

 (Endermic method). ] 



[Drugs may be applied locally where the epidermis is intact epidermic method as wiien 

 drugs which affect the sensory nerves of a part are painted over a painful area to diminish the 

 pain. Another method, the hypodermic, now largely used, is that of injecting, by means of a 

 hypodermic syringe, a non-corrosive, non-irritant drug, in solution, into the subcutaneous 

 tissue, where it practically passes into the lymph spaces and comes into direct relation with 

 the lymph- and blood-stream ; absorption takes place with great rapidity, even more so than 

 from the stomach.] 



Gases. Under normal conditions, minute traces of are absorbed from the air ; hydrocyanic 

 acid, sulphuretted hydrogen CO, C0. 2 , the vapour of chloroform and ether may be absorbed 

 (Chaussier, Gerlach, Rohrig). In a bath containing sulphuretted hydrogen, this gas is absorbed, 

 while C0 2 is given off into the water (Rohrig). 



Absorption of watery solutions takes place rapidly through the skin of the frog (Guttmann, 

 W. Stirling, v. Wittich). Even after the circulation is excluded and the central nervous system 

 destroyed, much water is absorbed through the skin of the frog, but not to such an extent as 

 when the circulation is intact (Spina). 



Galvanic Conduction through the Skin. If the two electrodes of a consta?it current be im- 

 pregnated with a watery solution of certain substances and applied to the skin, and if the 

 direction of the current be changed from time to time, strychnin may be caused to pass through 

 the skin of a rabbit in a few minutes, and that in sufficient amount to kill the animal (If. Munk). 

 In man, quinine and potassium iodide have been introduced into the body in this w T ay, and 

 their presence detected in the urine. This process is called the cataphoric action of the con- 

 stant current ( 328). 



290. COMPARATIVE HISTORICAL. In all vertebrates, the skin consists of chorium 



2f 



