ACTION OF THE GASTRIC JUICE. 223 



fatty matter, sometimes in the form of oil and sometimes enclosed in vesicles, 

 constituting adipose tissue ; gelatine and animal matters in a liquid form 

 extracted from meats, as in soups ; caseine, in its liquid form united with 

 butter and salts in milk, and coagulated in connection with various other 

 matters, in cheese ; vegetable nitrogenized matters, of which gluten may be 

 taken as the type ; vegetable fats and oils ; sugars, both from the animal and 

 vegetable kingdoms, but chiefly from vegetables ; the different varieties of 

 amylaceous substances ; and finally, organic acids and salts, derived chiefly 

 from vegetables. These matters, particularly those from the vegetable king- 

 dom, are united with more or less innutritions matter, such as cellulose. 

 They are also seasoned with aromatic substances, condiments etc., which are 

 not directly used in nutrition. 



The various articles described as drinks are taken without any consid- 

 erable admixture with the saliva. They embrace water and the various 

 nutritious or stimulant infusions (including alcoholic beverages) with a small 

 proportion of inorganic salts in solution. 



Action of the Gastric Juice upon Meats. There are three ways in which 

 the action of the gastric juice upon the various articles of food may be studied. 

 One is to subject them to the action of the pure fluid taken from the stomach, 

 as was done by Beaumont, in the human subject, and by Blondlot and others, 

 in experiments upon the inferior animals ; another is to make use of prop- 

 erly prepared acidulated extracts of the mucous membrane of the stomach, 

 which have been shown to have many of the properties of the gastric juice, 

 differing mainly in activity ; and another is to examine from time to time the 

 contents of the stomach after food has been taken. By all of these methods 

 of study it has been shown that the digestion of meat in the stomach is far 

 from complete. The parts of the muscular structure most easily attacked* 

 are the fibrous tissue which holds the muscular fibres together, and the sar- 

 colemma, or sheath of the fibres themselves. If the gastric juice of the dog 

 be placed in a vessel with finely chopped lean meat and be kept in contact 

 with it for a number of hours at about 100 Fahr. (37'78 C.), agitating the 

 vessel occasionally so as to subject, as far as possible, every particle of the 

 meat to its action, the filtered fluid will be found increased in density, its 

 acidity diminished, and presenting all the evidences of having dissolved a 

 considerable portion of the tissue. There always, however, will remain a cer- 

 tain portion which has not been dissolved. Its constitution is nevertheless 

 materially changed ; for it no longer possesses the ordinary character of 

 muscular tissue, but easily breaks down between the fingers into a pultaceous 

 mass. On subjecting this residue to microscopical examination, it is found 

 not to contain any ordinary fibrous tissue ; and the fibres of muscular tissue, 

 although presenting the well marked and characteristic striae, are broken into 

 short pieces and possess very little tenacity. It is evidently, only the muscu- 

 lar substance which remains ; the connective tissue and the sarcolemma hav- 

 ing been dissolved. These facts have been repeatedly noted, and even on 

 adding fresh juice to the undigested matter, it is not dissolved to any con- 

 siderable extent, the residue not being sensibly diminished in quantity, and 



