PERSPIRATORY GLANDULE. 525 



from the body is Erismann, 1 who examined them both in the dead and in the 

 living bodv. In the dead body he found that the amount of fluid evaporat- 

 ing from a given area of the skin was the same whether the under surface 

 was in contact with serum or with water, and whether the vessels were fully 

 injected with water or not. The amount increased rapidly with temperature 

 and with the dry ness of the air, but it made little difference whether 1000 

 or 0000 litres of air passed over the surface in a given time. Evaporation 

 took place most actively from those parts which contained many sweat- 

 glands; the skin of the sole of the foot, for example, which contains, accord- 

 ing to Krause, 2685 sweat-glands in the square inch, yielding nearly double 

 the amount of insensible perspiration as compared with the skin of the belly, 

 which has only 1136 in that area, notwithstanding the much greater thick- 

 ness of the epithelium in the former situation. A dead body (the size of 

 which is not given) of a woman lost 617.6 grains in 24 hours, the tempera- 

 ture being 60 F., and the amount of aqueous vapor in the air 64 per cent, 

 (as compared with saturation). Experiments made upon the liviixj body 

 showed that the most important external factor in determining the amount 

 of evaporation was the relative dry ness or moisture of the air. Next came 

 the temperature, and then the ventilation or amount of air blowing over the 

 surface. The imbibition of a large quantity of hot fluid, by filling the ves- 

 sels and increasing the pressure, augmented the evaporation. It was also 

 increased by work, even though sweating did not occur. Considerable dif- 

 ference of opinion exists as to whether the insensible perspiration is dis- 

 charged by the surface of the skin generally (Krause, Bonders), or whether 

 this is not the exclusive province of the sweat-glands. Erismann adduces 

 many reasons in favor of the latter view, and it may at least be admitted 

 that the greater part of the "insensible" and all the "sensible" perspiration 

 is eliminated by these glands. 



422. That the Cutaneous excretion is to a certain extent vicarious with 

 the Urinary in regard to the amount of fluid eliminated, has been generally 

 admitted, and is probably true; but the observations of Weyrich have shown 

 that under similar conditions, avoiding extremes, both excretions rise and 

 fall together, and that, consequently, no deductions can be drawn as to the 

 amount of perspiration given off from any estimates of the volume of urine 

 'discharged. We must not disregard the circumstance, however, that these 

 two excretions are to a certain extent vicarious, in regard to the elimina- 

 tion of the products of the "waste" of the system. Leube" has in particular 

 shown that in certain affections of the kidneys the skin exudes urea, phos- 

 phoric icid, and chlorine in excess, whilst the quantity of these compounds 

 appearing in the urine is correspondingly diminished. The share which the 

 Skin has in this office has probably been generally underrated. As we have 

 seen ( 421), there is reason to believe that at least 100 grains of azotized 

 matter are excreted from it daily; and any cause which checks this excre- 

 tion must throw additional labor on the kidneys, and will be likely to pro- 

 duce disorder of their function. From the experiments of Scharling and 

 Hannover, it would appear that the proportion of Carbonic acid eliminated 

 by the Skin is to that discharged by the Lungs as 1 : 38. Aubert, however, 

 gives a much smaller proportion, viz., as 1 : 200 (see p. 395). Reinhardt 3 

 estimates the daily amount of Carbonic acid eliminated by the whole skin 

 of an adult, by calculation from experiments made on one of his arms, at 

 from 33 to 36 grains, and Rohrig found that the skin of one arm yielded 

 half a grain of Carbonic Acid gas per hour. The secreting action of the 



1 Erismann, Zur Physiologic der "Wasserverdunstung von der Haul, in the Zeit- 

 schrift f. Biologie, Bd.xi, 1875, pp. 1-78. 



2 Deutsche Archiv f. Klin. Med., Bd. vii, p. 1. 3 Zeits. fur Biol., 1869, p. 28. 



