SWEAT. 



841 



state either the object of the vascular glands 

 in general, or that of the supra-renal capsules 

 in particular. Pathological study also has, 

 up to the present time, failed to afford any- 

 thing which would allow any safe conclu- 

 sion to be drawn concerning the function of 

 the supra-renal capsules. By their concealed 

 situation, they elude the experiments of the 

 physiologist ; besides this, they are so small, 

 that their secretion can scarcely have any very 

 sudden and visible influence on the vegetative 

 life of the body. So that even by such an 

 eager operative interference as the extirpation 

 of this gland, the wished-for result might 

 scarcely be obtained. 



I therefore repeat, that at present we are 

 completely in the dark as to the function of 

 the supra-renal capsules ; we know not at all 

 in what way they operate, and on this account 

 all references of the supra-renal capsules to 

 this or that organ such as have so often 

 been made are altogether empty and worth- 

 less. We may see at a glance that it would 

 be just as correct to assign a relation of the 

 supra-renal capsules to the eye or ear, as to 

 the sexual or urinary organs. 



Ecker, who, in opposition to our view, re- 

 gards the secretion of all the vascular glands 

 as one and the same, keeps its contents of fat 

 and protein compound especially in view, and 

 conjectures that all the vascular glands are 

 adapted to the formation from the blood of a 

 secretion which is rich in protein and fat, and 

 which being subsequently retaken into the 

 current of the blood, in this manner benefits 

 nutrition. But apart from the fact, that one 

 cannot see why such a fluid should take this 

 round-about way through the vascular glands ; 

 apart from this, the quantity of protein com- 

 pounds in the secretion of all the vascular 

 glands of the body, even if we take this at 

 the highest estimate, is far too small to render 

 any enrichment of albuminous materials which 

 the body could obtain in this way other than 

 a very inconsiderable one. The want of an 

 excretory duct affords certainly this informa- 

 tion, that the secretion prepared by the vesicles 

 of the vascular glands is again received into 

 the blood ; but even this notion has connected 

 with it much that is obscure and uncertain. 



The difference of the function of the vascular 

 glands is yet further upheld by the circum- 

 stance that their vital duration and activity is 

 different. The function of the thymus is the 

 first to wane ; that of the supra-renal capsules 

 seems likewise much diminished in more 

 advanced age ; while, on the contrary, the 

 activity of the spleen endures for the whole 

 life. These organs experience an excessive 

 deposit of fat in their vesicles, and by this 

 means gradually disappear. 



(Heinrich Frey.} * 



SWEAT. The cutaneous secretion is 

 formed by the spiral sudoriferous canals dis- 

 covered by Breschet and Purkinge. In con- 



* The Editor begs to make his acknowledgments 

 to his friend Dr. Brinton for this translation from 

 the German MS. of Professor Frey. 



sidering this subject it is important to make 

 the distinction between sweat and that ex- 

 halation which is constantly, and at the same 

 time insensibly, excreting from the healthy 

 skin. The latter is the manifestation of a 

 function indispensably necessary for the con- 

 tinuance of life; while sweat may be regarded 

 merely as an occasional result, and as pro- 

 ducing on the surface certain excretive pro- 

 ducts which under ordinary conditions only 

 appear in small proportion on the skin, and 

 find their more natural exit from the organism 

 through other channels. It is true that sweat 

 contains among its constituents the ordinary 

 products of the insensible perspiration, but it 

 also contains other matters of a solid kind 

 which do not appear in a fluid form unless 

 cutaneous excitement be brought about, and 

 which in cold weather and in the case of in- 

 dolent, inactive persons, adhere to the cuticle, 

 and are gradually rubbed or washed off. 

 These solid matters are not volatile at the 

 ordinary temperature of the skin, and there- 

 fore will not pass off from the body in mate- 

 rial quantity by any amount of perspiration. 

 They become constituents of sweat, however, 

 inasmuch as they dissolve in the water which, 

 under exercise or owing to excessive tempe- 

 rature, appears on the surface. Thus sweat 

 is constituted of the ordinary aqueous pro- 

 ducts of the natural perspiration, which ap- 

 pearing in large quantity ceases to be va- 

 porised, and in addition it contains those 

 cutaneous secretions which the water dis- 

 solves, but which, when an animal does not 

 sweat, appear in less quantity, and adhere 

 undissolved to the surface. As the ordinary 

 cutaneous transpiration forms an important 

 part of sweat, I shall proceed to consider it 

 before entering on the more immediate subject 

 of the present article. 



In the healthy human subject, a portion of 

 water is constantly finding its way to the 

 surface, and under ordinary conditions is va- 

 porised nearly as fast as it is secreted. Some 

 difference is observed in individuals in this 

 respect, however, so that we observe some 

 whose skins are constantly moist, while others, 

 though in perfect health, have the skin almost 

 always dry, yet doubtless performing its ordi- 

 nary function. Perhaps the most agreeable 

 proportion of perspiration, and that which we 

 should regard as approaching more nearly to 

 the normal quantity, is that which maintains 

 a certain moisture on the surface sufficient to 

 impart an agreeable softness to the touch, and 

 scarcely to convey the idea of moisture. 

 Many attempts have been made to determine 

 the quantity of the cutaneous transpiration, 

 and perhaps nothing has ever been attempted 

 so unpromising in result. It is almost certain, 

 indeed, that we do not transpire equally 

 during any two minutes of the day, and on no 

 two days alike. 



Sanctorius, the Venetian physician, whose 

 aphorisms contain much valuable matter, too 

 much neglected by the physiologists of the 

 present day, made lengthened experiments on 

 perspiration. The insensible perspiration has, 



