GASTRIC DIGESTION. 425 



commenced over the surface of the meat. In fifty minutes, the fluid had be- 

 come quite opaque and cloudy; the external texture began to separate and 

 become loose. In sixty minutes, chyme began to form. At 1 o'clock P. M. 

 (digestion having progressed with the same regularity as in the last half hour), 

 the cellular texture seemed to be entirely destroyed, leaving the muscular fibres 

 loose and unconnected, floating about in fine small shreds, very tender and soft. 

 At 3 o'clock, the muscular fibres had diminished one-half, since the last exami- 

 nation. At 5 o'clock, they were nearly all digested; a few fibres only remain- 

 ing. At 7 o'clock, the muscular texture was completely broken down, and 

 only a few of the small fibres could be seen floating in the fluid. At 9 o'clock, 

 every part of the meat was completely digested. The gastric juice, when taken 

 from the stomach, was as clear and transparent as water. The mixture in the 

 vial was now about the color of whey. After standing at rest a few n^nutes, a 

 fine sediment of the color of the meat subsided to the bottom of the vial. A 

 piece of beef, exactly similar to that placed in the vial, was introduced into the 

 stomach, through the aperture, at the same time. At 1*2 o'clock it was with- 

 drawn, and found to be as little affected by digestion as that in the vial ; there 

 was little or no difference in their appearance. It was returned to the stomach; 

 and, on the string being drawn out at 1 o'clock P. M., the meat was found to 

 be all completely digested and gone. The effect of the gastric juice on the 

 piece of meat suspended in the stomach, was exactly similar to that in the vial, 

 only more rapid after the first half hour, and sooner completed. Digestion 

 commenced on, and was confined to, the surface entirely in both situations. 

 Agitation accelerated the solution in the vial, by removing the coat that was 

 digested on the surface, enveloping the remainder of the meat in the gastric 

 fluid, and giving this fluid access to the undigested portions." 1 Many variations 

 were made in other experiments ; some of which strikingly displayed the effects 

 of thorough mastication, in aiding both natural and artificial digestion. 



449. The attempt was made by Dr. Beaumont to determine the relative 

 digestibility of different articles of diet, by observing the length of time requisite 

 for their solution. 3 But, as he himself points out, the rapidity of digestion 

 varies so greatly, according to the quantity eaten, the nature and amount of the 

 previous exercise, the interval since the preceding meal, the state of health, the 

 condition of the mind, and the nature of the weather, that a much more ex- 

 tended inquiry would be necessary to arrive at results to be depended on. Some 

 important inferences of a general character, however, may be drawn from his 

 inquiries. It seems to be a general rule, that the flesh of wild animals is more 

 easy of digestion, than that of the domesticated races wWch approach them most 

 nearly. This may, perhaps, be partly attributed to the small quantity of fatty 

 matter that is mixed up with the flesh of the former, whilst that of the latter is 

 largely pervaded by it. For it appears from Dr. B/s experiments, that the 

 presence in the stomach of any substance which is difficult of digestion, inter- 

 feres with the solution of food that would otherwise be soon reduced. It seems 

 that, on the whole, Beef is more speedily reduced than Mutton, and Mutton 

 sooner than either Veal or Pork. Fowls are far from possessing the digestibility 

 that is ordinarily imputed to them; but Turkey is, of all kinds of flesh except 

 Venison, the most soluble. Dr. Beaumont's experiments further show, that 

 bulk is as necessary for healthy digestion, as the presence of the nutrient prin- 



1 Experiments 2 and 3 of First Series. 



2 It is important to bear in mind that the digestibility of different substances bears no 

 relation to their nutrient value, which is entirely dependent on their chemical composition. 

 Of course, however nutritious a substance may be, it is valueless as an article of diet if it 

 cannot be dissolved ; but, on the other hand, substances which are very easily digested 

 (such as farinaceous matters) may have a low nutritive value, though containing but a 

 very small proportion of azotized constituents. 



