DIGESTIBILITY OF FOOD. 317 



for it is not till the connective tissue has been dissolved that the 

 gastric juice is able to act, through the openings made in it, upon 

 the sarcolemma and primitive bundles (see vol. ii, p. 127). On 

 this account, true muscle does not actually belong to the class of 

 easily digested substances. Frerichs found in the stomach of a 

 cat, four hours after feeding, pieces of raw beef which were only 

 softened on the surfaces. When portions of flesh, inclosed in a 

 fine muslin bag, were introduced through a fistulous opening into 

 the stomach of a dog, they did not thoroughly disappear until 

 after an interval of from five to eight hours. 



It has generally been regarded as an established fact that raw 

 flesh is much more difficult of digestion than boiled or roast meat ; 

 the difference is not, however, very considerable, and it has been 

 estimated by Frerichs at only half an hour. Nor need we wonder 

 at this, for the advantage derived from the boiling or roasting, by 

 which the connective tissue is loosened and the organic structure 

 is partly destroyed, is in part counteracted by the albumen of the 

 muscular juice as well as the syntonin being reduced to a state of 

 coagulation. The above-mentioned jelly-like swelling-up of the 

 syntonin in acid fluids may, perhaps, in a great measure contribute 

 towards the difficult digestibility of raw meat. 



We have formerly had occasion to observe, that after an animal 

 diet, muscular fibres, although in various phases of metamorphosis, 

 may be distinctly recognised along the whole course of the 

 intestinal canal ; hence we see that the digestion of flesh is by no 

 means completely effected in the stomach, and that its most im- 

 portant histological element, the true muscular fibre, in association 

 with the sarcolemma, resists for the longest period the action of 

 the digestive fluids ; indeed, during an abundant flesh diet, we find 

 a large number of muscular fibres, morphologically unchanged, in 

 the excrements. Hence in the case of flesh we can form no con- 

 clusion regarding its digestibility from the duration of its retention 

 in the digestive organs. When dogs are fed solely with flesh, we 

 find that after 6 or 8 hours the greatest part has usually disap- 

 peared, although small portions often remain in the stomach for 

 10 or 12, or even 16 or 20 hours. In their observations on a dog 

 with a fistulous opening at about the middle of the small intestine, 

 Bidder and Schmidt found that most substances escaped in 5 or 6 

 hours after a meal ; and very similar results were observed in a 

 man who was a patient in our hospital, and in whom there was 

 an intestinal fistula at the end of the ileum. We may therefore 

 assume that in the normal state the stomach is not engaged in the 



