Report on the progress of human anatomy and physiology in the year 1843-4 / [Sir James Paget].

  • James Paget
Date:
1845
Catalogue details

Licence: Public Domain Mark

Credit: Report on the progress of human anatomy and physiology in the year 1843-4 / [Sir James Paget]. Source: Wellcome Collection.

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    carefully distilled on a sand-bath 3875 grains of pure gastric fluid obtained after feeding his dog with raw meat; he repeated the distillation, and repeated the whole experiment, several times, with the gastric fluid of other animals as well as of the same dog, and the constant result was, that the product of the distillation did not once exhibit the slightest acid reaction; but the residue in the retort was always strongly acid. It was thus proved that the acid of the gastric fluid cannot be either the hydrochloric or the acetic, for both these are volatile at the boiling point of water, and would have distilled over. A further proof that it is neither of these nor lactic acid was furnished by the fact that no effervescence is produced when chalk, marble, or any other car¬ bonate of lime is added to the gastric fluid ; and it was this fact which chiefly led M. Blondlot to his conclusion, that the true and almost only source of the acidity of healthy gastric fluid is the presence of an acid phosphate [biphosphate ?] of lime. The evidence which he gives in addition to the above is : 1st, there is no acid salt, except this acid phosphate of lime which could retain its acidity and remain in contact with carbonate of lime without exciting decomposition; 2d, sul¬ phuric acid, added to gastric fluid, produces an abundant precipitate of sulphate of lime, and oxalic acid a similar one of oxalate of lime. 3. Potash, soda, am¬ monia, and lime-water, produce abundant precipitates of neutral phosphate of lime. 4. The calcined ash of gastric fluid was not deliquescent, was dissolved without effervescence by a few drops of hydrochloric acid, with which it formed chloride of calcium ; it had, therefore, contained neutral phosphate of lime, the excess of the acid having been decomposed in the calcination. The general conclusion of his analysis is, that the gastric fluid is composed of ninety-nine parts of water, with one part of acid phosphate of lime, acid phosphate of ammonia, chloride of sodium, mucus, an aromatic, and a peculiar, principle. Similar results were obtained from the analysis of the gastric fluid of several animals. For further evidence that the acid reaction of the gastric fluid depends on these acid phosphate salts alone, M. Blondlot has completely examined the question whether, during healthy digestion, lactic acid is ever formed by transformation of the food in the stomach. His conclusion is that neither it, nor a transformation of sugar into starch, nor any kind of fermentation takes place. He has often analysed the fluid expressed from food which had remained for various lengths of time in the stomach, and never found the least trace of lactic acid; and the reason he assigns for its absence is, that the acid of the gastric fluid prevents it, just as other acids prevent the lactic fermentation from taking place in a solution of sugar, provided they are present in proportion sufficient to give the solution a degree of acidity equal to that which it would acquire if the lactic acid were formed in it. In confirmation of this he shows, by numerous experiments on ruminants and birds, that lactic acid is formed by the transformation of the sugar of their food in all those parts of the digestive canal in which the food is delayed without the presence of an acid ; namely, in the first and second stomach of ruminants, the crops of birds, and the coecum of man and other animals. He first proves that the acidity often observed in the food taken from these cavities is not due to any secretion from their walls. He fed, for four days each, sixteen sheep and goats, and several pigeons and chickens with different kinds of food con¬ taining no sugar; and in every instance the portions of food which were found after twelve hours fasting, in the first stomach, or the crop, were not acid, but alkaline, proving that the walls of these cavities secrete an alkaline fluid. On the other hand, when, the other circumstances being the same, as many rumi¬ nants and fowls were fed on food containing sugar, the portions of food found in the same cavities were always acid, and, in the case in which they were analysed, the acid obtained was the lactic. In regard to the caecum he states that its contents are never more acid than those of the small intestines, except when the animals examined have, had sugar in their food ; from which, and the absence of any proof that the caecum secretes an acid fluid, he believes that the acidity often found is due to a portion of the