ITS COMPOSITION. 43 



Blondlot's method is a matter of very great difficulty) ; the 

 animal's licking does no harm, since it only keeps the wound clean. 

 The included portion of stomach soon becomes gangrenous 

 (generally from the third to the fifth day), and is then thrown off; 

 the fistula is then completed. To introduce a suitable canula into 

 the fistula, which shall neither fall out nor press too hard, nor 

 when closed shall allow fluid to escape from the stomach, is a 

 matter of much greater difficulty. For this purpose Bardeleben 

 has also contrived a very simple and useful apparatus, namely, 

 a silver tube, about three-fourths of an inch long, provided at 

 one end with a projecting border, in place of the double button- 

 like instrument used by Blondlot : into this tube there are fitted 

 two double hooks, united by a wire of the same length as the 

 canula ; by a well-fitting cork these hooks are so pressed upon the 

 walls of the canula, as to render it impossible for the whole appa- 

 ratus to escape from the wound. For further particulars regarding 

 details of manipulation, I must refer to Bardeleben's memoir. 



Pure filtered gastric juice contains only a small amount of 

 solid constituents, namely, from 1*05 to I' 48%; and hence they, 

 and especially the organic ingredients, have been very little 

 examined. 



In a specimen of human gastric juice collected by Beaumont, 

 Berzelius found l'27-- of solid constituents; in the gastric juice of 

 a dog, Blondlot found 1*00, and Leuret and Lassaigne 1*3 2; and 

 in that of a horse, Frerichs found 1*72. I have derived the above- 

 named numbers from experiments on the gastric juice of various 

 dogs ; it must, however, be remarked than on evaporation, the 

 gastric juice not only loses water, but also a comparatively large 

 quantity of hydrochloric acid, as will be seen from the experiments 

 presently to be described. Hence it was that Tiedemann and 

 Gmelin found that the solid constituents amounted to l'95% in the 

 gastric juice of a dog to whom carbonate of lime had previously 

 been administered, the hydrochloric acid being thus prevented 

 from escaping, and chloride of calcium being formed. 



Very different opinions have been held, up to the most recent 

 times, regarding the nature of the free acid of the gastric juice. 

 Prout was the first who instituted any serviceable chemical inves- 

 tigations regarding the gastric juice, and for a long time after the 

 publication of his results, the presence of free hydrochloric acid 

 in this fluid was regarded as established : it has, however, been 

 shown (in vol. i. p. 93) that free lactic acid is the predominating 

 acidifying agent in the stomach. 



