194 ANATOMY AND PHYSIOLOGY. 



the climate is sufficient to make the difference of color in the human 

 family. Is it capable of making the nose flat, skin jet black, and 

 hair like wool 1 The idea is ridiculous.. I see no theory so rational 

 as that which supposes that the different colors of nature, almost as 

 many shades and varieties as dialects, were formed at the very time 

 their language was altered or confounded, viz. at the tower of 

 Babel, and for the very wise reason that, as the people could not 

 converse together, their colors were correspondingly changed. 



The cutis, or true skin, is the third and most important layer. 

 Besides its uses already referred to, it has a very large supply of 

 blood sent to it ; is a surface of great sensibility, intimately sym- 

 pathizing with the internal organs ; and, from its exposed situation 

 and extent, is peculiarly liable to be affected by external influences. 

 Perhaps no other surface in the body is so much concerned in the 

 production of internal inflammatory disorders, and perhaps the 

 agents that above all others tend to produce these, are the various 

 degrees, and especially the sudden applications, of heat and cold. 

 When heat is applied suddenly and extensively, so as to give rise 

 to a burn or scald, the heart's action is frequently extinguished 

 within a few hours, even although the burn, in any one portion, is 

 altogether superficial and unimportant. Mr. John Hunter gives a 

 striking proof of the effects produced by a sudden change of tempera- 

 ture on the skin. He took an eel, which was swimming in water a 

 little above 30 degrees, and plunged it into water about 60 degrees, 

 a temperature in which it habitually lives with ease. The sudden 

 change, however, gave such a check to its system, that the animal 

 instantly expired.* In these cases the effect seems to be produced 

 principally through the agency of the nervous system ; but when 

 the application of cold produces its injurious effects, the blood that 

 is forced, by the constricted vessels, from the surface, upon the 

 internal parts, overloads them, and impedes the due performance of 

 their functions. Hence the indispensable importance of recalling 

 it back to the surface instead of abstracting. This theory over- 

 turns the old allopathic doctrine of blood-letting. When the body 

 is exposed for some time to a great degree of cold, the tendency to 

 sleep becomes almost irresistible. Under these circumstances, to 



* Says a writer " We lately met with a case exemplifying the effect of sudden 

 change of temperature. A person who had been treading snow in an ice-house felt his 

 feet uncommonly cold. To remedy this, he plunged them into water somewhat heated. 

 The consequence was, the little toe of one foot and part of the great toe of the other 

 mortified, and had to be cut off." 



