278 DIGESTION. 



of a living frog, and the parts were sensibly acted upon by 

 the gastric juice, even while the animal was alive and active. 1 

 A still more striking experiment was made by Dr. F. "W. Pavy, 

 who introduced through a fistulous opening into the stom- 

 ach of a dog in full digestion, one of the ears of a rabbit, 

 taking care to avoid mechanical injury, and obstructing the 

 circulation in the part as little as possible. At the end of 

 two hours, several large spots of erosion were observed upon 

 the ear ; and at the end of four and a half hours, rather more 

 than half an inch of the tip had been removed, " a small 

 fragment only being left attached by a narrow shred to the 

 remainder of the ear." 2 



Bernard denies the protective influence of the "living 

 principle," as advanced by Hunter, and attributes the im- 

 munity of the stomach from digestion during life to the pres- 

 ence of a coating of mucus and epithelium, the latter being 

 continually dissolved by the gastric juice, but renewed as fast 

 as it is destroyed. According to this supposition, as soon as 

 life ceases, the epithelium being no longer renewed, the coats 

 of the stomach are attacked, if any gastric juice exist in its 

 cavity. The finger, when introduced into the living stomach 

 through a fistula, is not acted upon, because its epidermic 

 covering is not capable of being dissolved by the gastric juice ; 

 and the legs of the living frog are digested because the epi- 

 thelium is not readily restored after it is removed. 3 This 

 explanation is unsatisfactory, for several reasons. In the first 

 place, it is simply a gratuitous supposition that the epithe- 

 lium of the stomach is constantly destroyed by the gastric 

 juice, and is as constantly reproduced. Again, in cases of ul- 

 ceration of the stomach, or other structural diseases in which 

 portions of the mucous membrane are deprived of epithelium, 

 the parts thus denuded are not acted upon by the gastric juice 

 during life ; and furthermore, Pavy has shown by experi- 



1 BERNARD, Lemons de Physiologie Experimentale, Paris, 1856, p. 408. 



PAVY, op. cit., p. 162. 

 8 BERNARD, op. cit., p. 404 ft seq. 



