244 



DIGESTION. 



fresh juice to the undigested matter, we have been unable to dissolve it to any considerable 

 extent, the residue not being sensibly diminished in quantity, and the muscular substance 

 always presenting its characteristic striae, on microscopical examination. 



Although it is stated by many, in a general way, that the nitrogenized alimentary 

 principles are digested by the gastric juice, a review of actual experiments will show that 

 the digestion of meat in the stomach is substantially such as we have just indicated. 

 Beaumont, in his experiments on artificial digestion, while he frequently states that the 

 meat is completely digested, describes the mixture, after a digestion of eight or nine hours, 

 as about the color of whey and depositing a fine sediment of a reddish color after standing 

 for a few minutes. In no case does he distinctly state that meat is ever completely dis- 

 solved. Pappenheim examined animal matters, especially muscular tissue, in various 

 stages of digestion by the gastric juice, and noted the disintegration of the tissue and 

 division of the muscular fibres into fragments, but not the solution of the true muscular 

 substance. Burdach describes the digestion of meat as consisting in the solution of its 

 cellular tissue, which is dissolved, first separating the muscular fibres, and finally being 

 converted into a pultaceous mass, more or less brown. The same facts, essentially, have 

 been noted by Bernard in experiments with the gastric juice of different animals. This 

 observer has found that the fluid from the stomach of the rabbit or the horse is much 

 inferior, as regards the activity of its action upon meat, to the gastric juice of the dog. 

 He compares the disintegrating process which takes place in the stomach to the action 

 of boiling water in cooking. 



I 



I 



FIG. 62. Matters taken from the pyloric portion of tlie stomach of a dog during digestion of mixed food. 



(Bernard.) 



a, disintegrated muscular fibres, the striae having disappeared ; &, c, muscular fibres, in which the striae have partly 

 disappeared ; cZ, cZ, d, globules of fat ; e, e, e, starch ; g, molecular granules. 



Whether the gastric juice be entirely incapable of acting upon the muscular substance 

 or not, the above-mentioned facts clearly show that muscular tissue is usually not com- 

 pletely digested in the stomach. The action in this organ is to dissolve out the inter- 

 muscular fibrous tissue and the sarcolemma, or sheath of the muscular fibres, setting the 

 true muscular substance free and breaking it up into small particles. The mass of tissue 

 is thus reduced to the condition of a thin, pultaceous fluid, which passes into the small 

 intestine, where the process of digestion is completed. As far as a great part of the true 

 muscular substance is concerned, the action in the stomach is preparatory and not final. 



