278 PERSPIRATION. 



was instantly felt, and occasioned a paroxysm of rage. f Now 

 sensibility cannot be acquired by a part not already alive. 



Hair often grows abundantly in portions of the skin usually not 

 much supplied with it, and these are generally of a brown colour : 

 it will sometimes grow in parts naturally destitute of it, as the 

 tongue and even the heart.s Sometimes it grows in encysted 

 tumours, accompanied by fat, and occasionally by teeth and por- 

 tions of jaw and amorphous bone ; and feathers covered by fat 

 are sometimes found in the thorax and abdomen of tame geese 

 and ducks. h Hair has also been discharged from the urethra. 1 

 It has many times been seen blue as well as green. k 



The skin produces chemical changes similar to those which 

 occur in the lungs ! , and, like them, forms a watery secretion 



f 1. c. ibid. 



8 See references in Dr. Good's Study of Medicine, (4th edit.) vol. iv. p. 525.. 



h Blumenbach, Comparative Anatomy, 138. 



1 Phil. Trans, abridg. vol. v. and ix. 



k Various instances of both kinds in man and horse are collected by Dr, 

 Speranza, 1. c. Horses have had curly hair. Otto, 1. c. 



1 " W. Bache, On the Morbid Effects of Carbonic Acid Gas on Healthy Animals. 

 Philadel. 1794. 8vo. p. 46. Abernethy, 1. c." Cruikshanks on Insensible Per- 

 spiration, and Ellis, Further Inquiry on the Changes produced in Atmosj)heric Air, 

 &c. Others have questioned this, but no one doubts the fact in regard to cold- 

 blooded animals. Dr. Edwards found the surface of frogs and salamanders to 

 carbonise the air (1. c. p. 12.). Frogs are amphibious. They live indefinitely in 

 extensive or renewed water, and die if it is de-aerated, or not changed (p. 41. 

 sqq. ) ; as also do aquatic salamanders and the common toad. If their lungs are 

 removed, they still live indefinitely in such water or in air, and die if no air has 

 access to their skin, or the water is not purified enough (p. 71.) ; and die sooner 

 as they are younger and smaller. Although frogs live in air, mere respiration 

 appears insufficient after a time ; some application of air or aerated water to 

 the surface is also requisite to their life. That they live so long inclosed in wood 

 or mineral substances, as is commonly known, appears owing to the opposition 

 afforded, under these circumstances, to transpiration, which, in the open air, is so 

 great as speedily to dry them up, while, at the same time, the closeness is not 

 such as to entirely exclude air (p. 13.). They die in vacuo. 



In a limited quantity of water, they die sooner the higher the temperature 

 (p. 25. sqq.) ; and they support a high temperature better, if previously subjected 

 for some time to a cold temperature (p. 33. sqq.). Although their skin be care- 

 fully moistened, they cannot live without respiration in summer (p. 91.)- I* 

 appears from Dr. Edwards's experiments to be a general fact among animals, 

 that the want of air is best borne in a low temperature. The general good effect 

 of the application of cold in asphyxia by carbonic acid, is well known. The 

 greater the external heat, on the contrary, the more is air required by the skin and 



