THE GASTRIC FLUID. 



199 



The organic substance to which the gastric fluid Fig- no. 



mainly owes its property in aid of digestion, is 

 called pepsin. It is closely allied to the albumi- 

 nous compounds. 



The free acid of the gastric juice is partly the 

 hydrochloric and partly the lactic acid (p. 61). 

 The former constitutes, on the average, 0.35 per 

 cent., and the latter 0.45 per cent, of the fluid. 

 The hydrochloric acid usually does not appear 

 till some time after digestion has commenced. 

 (Lehmann.) 



Of the mineral constituents of gastric juice, the 

 chlorine compounds are the most abundant. The 

 chlorides of sodium, ammonium, calcium, magne- 

 sium, and iron are found in it. 



Accidentally, also, iodide and ferrocyanide of 

 potassium, salts of iron, and urea may exist in 

 gastric fluid. 



Experiments lead to the conclusion that dogs 

 secrete in twenty -four hours an amount of gastric 

 fluid equal to one- tenth their weight. This would 

 give a range between 12 and 18 pounds for a 

 man. Lehmann states, however, that, "according 

 to several direct observations on a woman, as 

 much as one-fourth of the weight of the body has 

 been found to be secreted as gastric fluid" 1 ! ! ! Of course this is all 

 secreted directly from the blood, and the latter is estimated by Leh- 

 mann to constitute but oneeighth of the 

 weight of the body. No further remark 

 appears necessary upon his estimate of the 

 gastric fluid. The quantity is increased by 

 aromatic substances, sugar, alcohol, and al- 

 kalies. It is not secreted at all during 

 fasting. 



Origin. Gastric fluid is secreted by the Gastric favuii (aiveoii), m the 

 epithelial cells of the peptic gastric glands * ^^ <; 

 (Fig. 110), as mucus is by the epithelial and i-zsoth of an inch broad; the 



^110,1 i T septa being l-1000th of an inch 



cells of other mucous membranes, as al- Wlde . 



Gastric peptic glands. 

 a. Common trunk. 6, 6. 

 Its chief branches, c, 

 c. Terminal coeca, with 

 spheroidal gland-cells. 



Fig. 111. 



Chemical Physiology, p. 168. 



