584 DIGESTION. 



tubes he placed in his axilla, in order that they might be exposed to the 

 same degree of heat as in the stomach ; and in the space of fifteen 

 hours, or of two days, more or less, the substances appeared to be 

 converted into chyme. In these experiments he found it important to 

 employ gastric juice, that had not been previously used, and to have a 

 sufficient quantity of it. 



From all these experiments, Spallanzani conceived it to be demon- 

 strated, that chymification is a true chemical solution ; and he endeavour- 

 ed to deduce from them the degree of digestibility of different alimentary 

 substances. Similar experiments were instituted by Dr. Beaumont. 1 In 

 all cases, solution occurred as perfectly in the artificial as in the real 

 digestions, but they were longer in being accomplished, for reasons which 

 appear sufficient to explain the difference. In the former, the gastric 

 secretion is not continuous; the temperature cannot be as accurately 

 maintained, and there is an absence of those gentle motions of the 

 stomach, which are manifestly so useful in accomplishing real diges- 

 tion. 



With regard to the precise nature of the gastric juice of Spallanzani, 

 we have already observed that great contrariety of sentiment has pre- 

 vailed ; and that, in ordinary cases, it is impracticable to procure it 

 unmixed with the other secretions of the digestive mucous membrane. 

 Spallanzani affirmed, that the only properties he detected in it, were, 

 a slightly salt, bitterish taste; it was neither acid nor alkaline. Gosse 2 

 found it vary according to the nature of the animal, whether herbivor- 

 ous or carnivorous; and to be always acid in the former. Dumas 3 

 held the same sentiments, and maintained from experiments on dogs ? 

 that it was acid or alkaline, according as the animal had fed on vege- 

 table or animal diet. He declared it, moreover, to be mawkish, thick, 

 and viscid. Viridet 4 and others affirmed that it was always acid. Mr. 

 Hunter 5 was not inclined to suppose, that there is any acid in the gastric 

 juice as a component or essential part of it, " although an acid is very 

 commonly discovered even when no vegetable matter has been introduced 

 into the stomach/' Scopoli 6 analyzed the gastric juice of the rook, and 

 found it to consist of water, gelatin, a saponaceous matter, muriate of 

 ammonia, and phosphate of lime. Carminati 7 describes it as salt, bitter, 

 and frequently acid; and MM. Macquart 8 and Vauquelin, 9 in the gastric 

 juice of the ruminant animal, found albumen and free phosphoric acid. 10 

 All these analyses were made on the mixed fluid, to which the term 

 gastric juice has been applied. That such a mixed fluid does exist in 

 the stomach at the time of chymification, and is largely concerned in 

 the process, is proved by the facts already mentioned, as well as by the 

 following. M. Magendie 11 asserts, that one of his pupils M. Pinel 



Op. citat., p. 139. a Experiences sur la Digestion, 81, Genev., 1783. 



Principes de Physiologie, Paris, 1806. 

 Tractatus Novus de Prima Coctione, &c., Genev., 1691. 



Observations on Certain Parts of the Animal Economy, with Notes by Prof. Owen, 

 Amer. edit., p. 134., Philad., 1840. 6 J n Spallanzani, 244. 



Ricerche sulla Natura, &c., del Succo Gastrico, Milano, 1785; or Journal Phys., t. xxiv. 

 Mem. de la Societe de Med., Paris, 1786. 9 Fourcroy, Elem. de Chim., tom.iv. 



10 See Burdach, Die Physiologie als Erfahrungsv/issenschaft,Y. 240 und431,Leips^ 1835* 



11 Precis, &c., ii. 11. 



