6 7 o SE CRE TION AND ABSORPTION B Y THE SKIN 
matter from imbibition of water ; in the one-horned, rhinoceros a gland opens on 
the posterior aspect of each foot. 
The function of the curious gland at the back of the thigh of male 
monotremes, supplying its secretion by a long. duct to the hollow horny spur on 
the heel (so like in arrangement to the poison gland and fang of a snake) is 
not known with certainty. 
There are glands in the skin of the male of the kangaroo, Halmaturus 
rufus, which secrete a red substance adhering to the hair, while the maxillary 
glands of the female dwarf antelope, Cephalolophus pygmceus, secrete a blue 
substance reddened by acid. 1 
Chemical Nature of Skin Secretions. 
(a) Watery secretions. — Naturally the composition of the sweat 
of man and mammals has received more attention than that of other 
skin secretions. 
Since the quantity of sweat secreted is dependent upon so many 
conditions, it is of little value to quote the numbers obtained by 
different observers, apart from a statement of the special conditions 
under which the observations took place. 
There are several methods of collecting the sweat of the whole body, 
or of special parts. Evaporation may be hindered by enclosing a part, 
such as the forearm and hand, in a rubber bag, and the sweat collected 
in a bottle tied into the lower end of the bag. 2 The subject may sit in a 
Pettenkofer and Voit's respiration chamber (but breathe through tubes 
to the exterior), and the water given off by the skin be calculated from 
the readings of hygrometers in the ingoing and outgoing currents of 
air. 3 Or the secretion of the skin may be stimulated by raising the 
temperature of the surrounding air, while the whole body, with the 
exception of the head, is enclosed in a convenient receptacle. 4 By 
the hot-air method, Argutinsky 5 collected a quarter of a litre of sweat 
in half an hour, at a temperature raised during the experiment from 
27° to 41° C. Schierbeck, 6 by the hygrometric method, calculated that 
in his own case, when clothed and at rest, the air in contact with the 
skin being at the normal temperature within clothing (32° C), 2 or 3 
litres of sweat were given off in twenty-four hours. No calculations of 
the total secretion of sweat can be made from local estimates, because the 
richness of various districts of the skin in sweat-glands is very different. 
In the body at rest the sweat is evaporated as fast as it is formed, 
and it is only under conditions exciting the glands to increased action, 
that the fluid collects upon the surface. 
In the resting condition of the body the temperature of the 
surrounding air must be raised to about 33° C. before the stimulus to 
increased activity of the sweat-glands is evoked. 7 
The following table is of interest as indicating that, at the time of 
1 Weber, Arch./, mikr. Anat., Bonn, 1888, Bd. xxxi. S. 499. For further information 
on such glands, see Owen, "Comparative Anatomy and Physiology of Vertebrata," London, 
1868, vol. iii. p. 632; Leydig, Ztschr.f. wissensch. Zool., Leipzig, 1850, Bd. ii. S. 1 (anal 
glands). 
2 Anselmino, Wagner's " Handwbrterbuch d. Physiol.," art. "Haut." 
3 Schierbeck, Arch. f. Physiol., Leipzig, 1893, S. 116. 
4 Favre, Compt. rend. Acad. d. sc, Paris, 1852, tome xxxv. p. 721. 
5 Arch./, d. ges. Physiol., Bonn, 1890, Bd. xlvi. S. 594. 6 Loc. cit. 
7 Schierbeck, loc. cit. 
