164 OF FOOD, AND THE DIGESTIVE PROCESS. 



curious movements of the stomach ; and that the continual removal, from its 

 cavity, of the matter which has been already dissolved, must aid the opera- 

 tion of the solvent on the remainder. The following is one out of many ex- 

 periments detailed by Dr. Beaumont. "At 1H o'clock A.M., after having 

 kept the lad fasting for 17 hours, I introduced a gum-elastic tube, and drew 

 oft' an ounce of pure gastric liquor, unmixed with any other matter, except a 

 small proportion of mucus, into a three-ounce vial. I then took a solid 

 piece of boiled recently-salted beef, weighing three drachms, and put it into 

 the liquor in the vial ; corked the vial tight, and placed it in a saucepan filled 

 with water, raised to the temperature of 100, and kept at that point on a 

 nicely-regulated sand-bath. In forty minutes digestion had distinctly com- 

 menced over the surface of the meat. In fifty minutes, the fluid had become 

 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 examination. At 5 o'clock, they were nearly all digested ; a few fibres 

 only remaining. 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 minutes, 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 

 twelve o'clock it was withdrawn, and found to be as little affected by digestion 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 por- 

 tions." 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. 



115. 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. 2 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 extended inquiry would be necessary to arrive at results to be 

 depended on. Some important inferences of a general character, however, 



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 com- 

 position. Of course, however nutritious n 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, 

 through containing but a very small proportion of azotized constituents. 



