2G2 THE HUMAN SKIN. 



to be admitted under the head of the insensible perspiration, and 

 which was reckoned different from the former, though now it is re- 

 garded as only the minimum of which the sensible sort is the max- 

 imum. We prefer the old classification, which marks a broad dis- 

 tinction both in the circumstances and form of the fluid. The one 

 is to the other what oil, or liquid, is to gas. As a writer has said : 

 " If we examine with a microscope the naked body, exposed during 

 summer to the rays of a burning sun, it appears surrounded with a 

 cloud of steam, which becomes invisible at a little distance from 

 the surface. And if the body is placed before a white wall, it is 

 easy to distinguish the shadow of that emanation." This emana- 

 tion, as the author calls it, constitutes a large proportion of what 

 the skin gives forth. Its functions are no doubt both purificatory 

 and anointing. It would seem to arise from the finer pores in the 

 skin, and from pores in the sides of the perspiratory and sebaceous 

 ducts ) for let us bear in recollection, that it is impossible to conceive 

 anything not porous, and the same principle of permeability which is 

 a physical fact in the external world, is an organic fact in the human 

 body, commencing from the skin. 



A ratio of size is required between the pores or passages, and the 

 sweats. This is partly insured by the varying contractility of the 

 former. But the difference between the sensible and insensible 

 perspiration is too great for this case to meet it. Different sized 

 pores are necessary. The condition of what transpires through the 

 skin, is touch. A fine perspiration would not be felt by too large 

 a pore, and the skin, when such perspiration passed, would know 

 nothing about it. The story of him who cut two holes in his barn 

 door, the one for the cocks and hens, and the other for the little 

 chickens, is no fable in the skin. Such a provision is indispensable 

 where the walls are feelings, and act as checktakers to whatever 

 goes in or comes out. 



But are our communications to the atmosphere limited to pro- 

 ducts which the senses can perceive, whether in small quantities or 

 volumes, in vapors or fluids? This question, not answered anato- 

 mically, is decided in the affirmative by broad facts, fertile of con- 

 sequences. What are those influences that carry contagion over 

 great spaces from skin to skin, and which no eye, or microscope, or 



