METHODS OF OBTAINING IT. 41 



quantity of saliva is always mixed with gastric juice obtained in 

 this manner. 



Formerly the only method of obtaining gastric juice in any 

 available quantity was to feed animals which had been for a long 

 time kept fasting, and to kill them in from 10 to 30 minutes after- 

 wards. If we employ bones, tendons, or large pieces of flesh, we 

 generally find in the stomach of the animal a gastric juice which is 

 very suitable for the purpose of experiment, since it possesses all 

 the properties of a normal gastric juice obtained in the preceding 

 manner ; if, however, the animals have been for a long time fasting, 

 rather more mucus is present; this is the only difference I have 

 ever observed. Tiedemann and Gmelin used no gastric juice in 

 their investigations which was not collected in this manner; but 

 in place of the above-named food they used irritant and insoluble 

 substances (pepper-corns and pebbles). 



It must be observed that this method answers very well with 

 carnivora and omnivora, but not with herbivora (unless with 

 ruminants) ; for in the latter, at all events, in rabbits, we often 

 find that after very prolonged fasting (even after the animal has 

 died from inanition), the stomach is still full of the remains of 

 food ; in this manner, however, we never obtain a pure gastric juice, 

 but one always containing saliva. Moreover, it is obvious that it is 

 not a very satisfactory or useful method, since we never obtain 

 from it more than a small quantity of gastric juice, and a large 

 number of animals must be killed in order to obtain a sufficient 

 quantity for the purpose of analysis or experiment. 



Spallanzani, Braconnot, and Leuret and Lassaigne, obtained 

 gastric juice without killing the animals, by making them swallow 

 sponges attached to a string, and after some time withdrawing them 

 from the stomach. Although these experimentalists, with the aid of 

 this method, made many beautiful observations, and threw much 

 light on the mysterious digestive fluid, the objections pertaining to 

 this means are so obvious as not to require mention ; the greatest 

 being that in this way we not only collect an impure gastric 

 juice, but that the quantity which we obtain is also very small. 



The third and best method is that which we first mentioned, 

 depending on the establishment of artificial gastric fistulae. After 

 Beaumont's* most admirable and decisive observations on gastric 

 digestion, which w r ere instituted on a man in whom a gastric 

 fistula had become formed, in consequence of a gun-shot wound, 



* Experiments and Observations on the Gastric Juice, and the Physiology of 

 Digestion. Boston, 1834. 



