556 OF SECRETION. 



under ordinary circumstances, being the product of simple Evaporation, by 

 which, of course, nothing but pure watery vapour is dissipated. 



701. The entire amount of fluid which is insensibly lost from the Cutaneous 

 and Pulmonary surfaces, is estimated by Seguin at 18 grains per minute ; of 

 which 11 grains pass off by the skin, and 7 by the lungs. The maximum 

 loss by Exhalation, cutaneous and pulmonary, during twenty-four hours, (ex- 

 cept under very peculiar circumstances,) is 5 Ibs.; the minimum 1 Ib. It 

 varies greatly, according to the condition of the atmosphere, and that of the 

 body itself. The manner and degree in which it is influenced by atmospheric 

 conditions, will be better discussed under the head of Animal Heat (731); 

 since this influence has a most important effect in the regulation of the tem- 

 perature of the body. As already pointed out, the Urinary excretion is in 

 great degree vicarious with it, in regard to the amount of fluid discharged, 

 the Urine being more watery in proportion as the Cutaneous Exhalation is 

 diminished in amount,~and vice versa ( 668). But we are also to look at 

 these two excretions as vicarious, in regard to the deportation (or getting rid) 

 of the products of the waste of the system. The share which the Skin has in 

 this office has probably been generally underrated. There is reason to believe 

 that at least 100 grains of azotized mater are excreted from it daily; and any 

 cause which checks this excretion must throw additional labour on the kid- 

 neys, and will be likely to produce disorders of their function. (See 714.) 



702. The Exhalant action of the Skin is influenced by general conditions 

 of the vascular and nervous systems, which are as yet ill understood. It is 

 quite certain, however, that through the influence of the latter the secretion 

 may be excited or suspended ; this is seen on the one hand in the state of 

 syncope, and in the effects of depressing emotions, especially fear, and its 

 more aggravated condition, terror; and on the other in the dry condition of 

 the skin during states of high nervous excitement. It is very probable that, 

 in many forms of fever, the suppression of the perspiration is a cause rather 

 than an effect of disordered vascular action; for there are several morbid 

 conditions of large parts of the surface, in which the suppression of the trans- 

 piration appears to be one of the chief sources of danger, having a tendency 

 to produce congestion and inflammation of internal organs. From the recent 

 experiments of Dr. Fourcault,* it appears that complete suppression of the 

 Perspiration in animals, by means of a varnish applied over the skin, gives 

 rise to a state termed by him Cutaneous Asphyxia; which is marked by 

 imperfect arterialization of the blood, and considerable fall of temperature, 

 ( 543, 726) ; and which, as it produces death in the lower animals, would 

 probably do the same in Man. A partial suppression by the same means 

 gives rise to Febrile symptoms, and to Albuminuria. 



703. The Skin is likewise furnished with numerous Sebaceous glands, also 

 distributed more or less closely throughout the whole surface of the body. 

 By these an Adipose secretion is poured forth, which keeps the skin from 

 being dried and cracked by the action of the sun and air. It is especially 

 abundant in the races which are formed to inhabit warm climates. Some of 

 these glandulse are simple follicles lined with secreting cells, and contained 

 in the substance of the Skin itself; whilst others are formed out of similar 

 follicles, more or less branched, elongated, and convoluted ; and others, again, 

 seem to consist of little else than clusters of Fat cells, from one part of which 

 an excretory duct arises ; these last commonly open into the passage by which 

 the Hair makes its way outwards. Besides these, there are other glands 

 situated in particular parts of the body, and having special functions. Such 

 are the Ceruminous glands situated beneath the skin of the auditory meatus ; 



* Comptes Rendus de 1'Acadcmie, May, 1844; and Lancet, June 8, 1844. 



