504 OF FOOD, AND THE DIGESTIVE PROCESS. 



inquiries ; which seem inconsistent Math the statement just given, especially in regard to the 

 presence of free muriatic acid. It may be well, in the first instance, to quote Professor 

 Dunglison's account of the analysis of the gastric fluid drawn from the stomach of Alexis 

 St. Martin, and supplied to him by Dr. Beaumont. " The quantity of free hydrochloric acid 

 was surprising ; on distilling the gastric fluid, the acids passed over, the salts and animal mat- 

 ter remaining in the retort ; the amount of chloride of silver thrown down, on the addition 

 of nitrate of silver to the distilled fluid, was astonishing. The author had many opportu- 

 nities of examining the gastric secretion obtained from the case in question. At all times, 

 when pure or unmixed, except with a portion of the mucus of the lining membrane of the 

 digestive tube, it was a transparent fluid, having a marked smell of hydrochloric acid ; and of 

 a slightly salt, and very perceptibly acid, taste." (Human Physiology, Sixth Edition, Vol. I., 

 p. 54G.) 



b. From the experiments of MM. Blondlot, Bernard, and Barreswill, and Dr. R. D. Thom- 

 son, on the other hand, it would seem that no free hydrochloric acid is present in the gastric 

 fluid; since the fluid which comes over, on distillation at a low temperature, contains none; 

 whilst the matter remaining in the retort becomes more and more acid with the progress of 

 the distillation, and may be subjected to a high temperature (300) without giving off acid 

 fumes. It is difficult to account for the discrepancy between these carefully conducted ex- 

 periments, and the positive statement of Professor Dunglison. otherwise than by supposing 

 that the Human gastric fluid differs from that of the Dog and the Pig, which were employed 

 in the analyses last quoted. The acid reaction was referred by Blondlot to the presence of 

 super-phosphate of lime; but this seems incorrect. Professor Thomson agrees with MM. 

 Bernard and Barreswill in attributing it chiefly to Lactic acid ; which, contrary to previous 

 opinions, they regard as generally if not universally present in the stomach during healthy 

 digestion, and it would seem that this acid may partially decompose the phosphates and 

 muriates, which are contained in the secretion : and may thus occasion the phosphoric and 

 muriatic acids to be set free. The presence of a small quantity of free Acetic acid, also, 

 seems to have been recognized by them. 



665. The Gastric Juice obtained from the stomach, was found by Dr. 

 Beaumont to possess the power of dissolving various kinds of alimentary sub- 

 stances, when these were submitted to its action at a constant temperature of 

 100, (which is about that of the stomach,) and were frequently agitated. 

 The solution appeared to be in all respects as perfect as that which naturally 

 takes place in the stomach ; but required a longer time. This is readily ac- 

 counted for when we remember, that no ordinary agitation can produce the 

 same effect with the curious movements of the stomach ; and that the conti- 

 nual removal from its cavity, of the matter which has been already dissolved, 

 must aid the operation of the solvent on the remainder. The following is 

 one out of many experiments detailed by Dr. Beaumont. "At 111 o'clock, 

 A.M., after having kept the lad fasting for 17 hours, I introduced a gum-elastic 

 tube, and drew off one 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 dis- 

 tinctly commenced 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 mus- 

 cular 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 colour of whey. After 



