INTESTINAL JUICE AND DIGESTION IN INTESTINE. 185 



Fig. 52. 



within the first hour contains gastric juice, and is turbid with the rem- 

 nants of disintegrated muscular tissue, mixed with fat vesicles and oil 

 drops. This turbid mixture grows constantly thicker and more gruelly 

 in consistency from the second to the tenth or the twelfth hour ; after 

 which the discharge of fluid from this part of the intestine becomes less 

 abundant, and finally ceases almost completely, as digestion comes to 

 an end. 



The gradual alteration in the ingredients of the food may also be 

 seen by killing the animal while digestion is going on, and examining 

 the contents of the alimentary 

 canal. If the food consisted of 

 muscular flesh and adipose tis- 

 sue, the stomach contains (Fig. 

 52) masses of softened meat, 

 smeared over with gastric juice, 

 and also a moderate quantity 

 of a grayish grumous fluid with 

 an acid reaction. This fluid 

 contains muscular fibres, iso- 

 lated from each other and more 

 or less reduced to imperfect 

 fragments. The fat vesicles of 

 the solid adipose tissue of beef 

 are but little altered, and there 

 are only a few free oil globules 

 to be seen floating in the mixed 

 fluids in the cavity of the 

 stomach. In the duodenum 

 the muscular fibres are further 

 disintegrated (Fig. 53). They 



become much broken up, pale, and transparent, but can still be recog- 

 nized, under the microscope, by their characteristic granular markings 

 and striations. The fat vesicles also begin to become altered in the 

 duodenum. The solid granular fat of beef and similar kinds of meat 

 becomes liquefied and emulsioned ; and appears under the form of free 

 oil drops and fatty molecules ; while the fat vesicle itself is partially 

 emptied, and becomes more or less collapsed and shrivelled. In the 

 middle and lower parts of the intestine (Figs. 54 and 55) these changes 

 continue. The muscular fibres become constantly more and more dis- 

 integrated, and a large quantity of granular debris is produced, which 

 is at last also dissolved. The fat also progressively disappears, and the 

 vesicles may be seen in the lower part of the intestine, collapsed and 

 empty. 



In this way the digestion of the different ingredients of the food goes 

 on in a continuous manner, from the stomach throughout the entire 

 length of the small intestine. At the same time, it results in the pro- 

 duction of three different substances, namely : 1st. Albuminose, produced 

 13 



CONTENTS OF STOMACH DURING DIGES- 

 TION OF MEAT, from the Dog. a. Fat Vesicle, 

 filled with opaque, solid, granular fat. b, b. Bits 

 of partially disintegrated muscular fibre, c. Oil 

 globules. 



