STOMACH AND INTESTINE. 



329 



Physical Properties. Pure gastric juice is a 

 structureless, limpid, and transparent fluid, of 

 a pale straw colour. Its taste is slightly 

 saline, and distinctly acid. And it has a pe- 

 culiar faint odour, which is probably charac- 



fDe Prima Coctione, Geneva, 1692), Brugnatelli 

 (Crell's Ann-ilen, 1787), and John Hunter (Animal 

 (Economy, 2nd ed. p. 205. 1792) had found that 

 the stomach contained an acid. Macquart (Memoires 

 de la Soc. Roy. de Medecine, 1786) stated this 

 acid to be phosphoric in the paunch of Ruminants. 

 Treviranus extracted the proventriculus of Birds 

 with water : he thus, amongst other results, was able 

 to confirm Hunter's conjecture, and regard it as 

 lactic acid (Biologie, vol. iv. p. 358. 1814). Chevreul 

 (Magendie's Physiologic, 1st & 2nd ed. 1825, vol. 

 ii. pp. 11, 12.) analyzed a fluid obtained by volun- 

 tary vomiting. He not only confirmed the presence 

 of lactic acid, but announced the presence of the 

 muriates of ammonia, potash, and soda; together 

 with an animal substance soluble in water, but not 

 in alcohol. 



In 1824, Prout led the way to a better knowledge 

 of this fluid by an analysis of the contents of the sto- 

 mach in Rabbits during digestion, in which he found 

 hydrochloric acid and chlorides (Philosophical Trans - 

 actions, 1824, pt. i. p. 45.). Dr. Children confirmed 

 this statement from the gastric fluid of a dyspeptic 

 patient (Annals of Philosophy, 1824, vol. viif. p. 68.). 

 Leuret and Lassaigne, however, using this latter 

 method, confirmed Chevreul as to the presence of 

 lactic acid (Recherches physiologiques et chemiques 

 pour servir a 1'Histoire de la Digestion. Paris, 1825.) 

 Tiedemann and Gmelin excited the secretion of 

 gastric juice by introducing stones into the stomachs 

 of animals, and found hydrochloric acid on examin- 

 ing the contents of the stomach after death (Die 

 Verdauung nach Yersuchen. Leipzig, 1831). In 

 1833-4, Beaumont's unique case afforded specimens 

 for three analyses ; by Dunglison, Silliman (Beau- 

 mont, Op. cit. pp. 69. et seq.), and Berzelius (An- 

 nuaire des Sciences chemiques, p. 282.). They all 

 essentially corroborated Prout (Annales de Chemie, 

 t. lix. p. 348.) ; as did Braconnot in 1835, with gastric 

 juice from the sponged stomach of animals. \Vas- 

 mann, in 1839, made some excellent experiments on 

 artificial digestion with an infusion of pig's stomach ; 

 but added little or nothing to our knowledge of 

 the gastric acid (Nonnulla de Digestione. Berolini, 

 1839). Huenefeld, adopting Prout's method, obtained 

 lactic acid (Chemismus in der Thierischen Organi- 

 zation. Leipzig, 1840) ; a result in which, as well as 

 in the cause of Prout's and Dunglison's view, Leh- 

 mann either preceded or confirmed him (Physiolo- 

 gische Chemie, 1840. Bd. i. p. 284.). Enderlin, 

 however, who examined the digesting stomach of a 

 beheaded criminal, and repeated Dunglison's process, 

 reasserted its results (Liebig's Annalen der Chemie 

 und Pharmacie, 1843. Bd. xlvi., p. 122.) In this year, 

 Blondlot imitated Beaumont's case, by instituting 

 fistulas in the stomachs of dogs; and announced 

 biphosphate of lime as the acid principle (Traite 

 Analytique de la Digestion. Paris, 1843). Lassaigne 

 (Journal de Chemie, 1844, pp. 73. 183.) ; and Bernard 

 and Barreswil (Comptes Rendus, 1844, t. xix. p.1285.) 

 made use of the same method ; but denied the accuracy 

 ot'Blondlot's chemical results in detail, and affirmed 

 the presence of lactic acid. Pelouze corroborated 

 some of their statements (Comptes Rendus, t. xix. 

 p. 1227.) ; as subsequently did Thomson also (Philo- 

 sophical Magazine, 1845, p. 419.). Schmidt next 

 asserted that the active principle of the gastric juice 

 was hydrochloric acid, modified by combination 

 with the digestive principle; but did not detail 

 the analyses on which this view was based (Annalen 

 der Chemie u. Pharmacie, 1847, Bd. Ixi. p. 311.). 

 Lehmann, in 1849, corroborated the lactic acid view, 

 by examinations of gastric juice from tistulae (Be- 

 richte der Gesell. der Wiss. zu Leipzig. Bd. i. 



teristic for each of the different* species of 

 animals, like the smell of the blood from 

 whence it is no doubt derived. 



Where, as is often the case, the gastric 

 juice is mixed with saliva, mucus, or relics of 

 the food, its appearances will of course differ 

 from those above described. The froth of the 

 saliva sometimes distinguishes this admixture. 

 The mucus thus added is ropy or viscid, and ge- 

 nerally presents scaly epithelium, which, toge- 

 ther with its neutral or alkaline character, betray 

 its origin from the mouth or oesophagus. Both 

 it and the fragments of food are frequently 

 deposited from the gastric juice, as a dirty 

 flocculent sediment. And they may always 

 be removed from it by careful filtration ; when 

 the fluid loses its greyish, brownish, or turbid 

 character. 



The specific gravity of the gastric juice was 

 observed by Silliman to be about 1005*0. But 

 from the condition of the specimen heexamined, 

 and the mode of weighing^ he adopted, very 

 little reliance can be placed on this state- 

 ment. Lassaigne J also made direct obser- 

 vations with the same view, and found that 

 the irritated empty stomach poured forth a 

 fluid of sp. gr. lOOl'O ; while that secreted on 

 the contact of flesh was 1005*0, and with bread 

 lOlO'O. But it must obviously be very difficult 

 directly to determine the specific gravity of 

 such a fluid, in the small quantities in which 

 it is generally obtained. The per-centage of 

 solid contents is more easily estimated. 

 Tiedemann and Gmelin rated it at T95 in 

 the gastric juice of a dog who had been made 

 to swallow small pieces of limestone ; and at 

 P6 in that of a horse. Berzelius gives it at 

 1*27 in the specimen sent him by Beaumont; 

 Lassaigne at T32, and Blondlot at TO, from 

 the gastric fistulae of dogs ; Frerichs (appa- 



pp. 100. et seq. ; and Op. cit. Bd. i. s. 97.). And 

 Frerichs about this time came to the same conclu- 

 sion (Wagner's Handwoerterbuch der Physiologic, 

 vol. iii. p. 815.) from similar experiments. 



But this comparative unanimity in favour of 

 lactic acid was not destined to last long. In 1851, 

 Huebbenet for the first time found a simple method 

 of preventing that admixture of saliva which had 

 hitherto rendered the gastric juice obtained in such 

 experiments with fistula? an impure secretion. This 

 he did by obliterating the ducts of the larger salivary 

 glands. And the researches which Bidder and 

 Schmidt instituted upon the gastric juice thus pro- 

 cured seem at length to have established, that it is 

 the hydrochloric which constitutes the proper acid of 

 the gastric juice. 



[In preparing the greater part of this essay for 

 the press, the author found it impossible to procure 

 a copy of Bidder and Schmidt's valuable Essay ; and 

 was hence only acquainted with such portions of it 

 as are mentioned in Lehmann's (Physiologist-he 

 Chemie, vol. iii.) recent work ; in the reports given 

 of Huebbenet's Dissertation by Scherer and Valen- 

 tin, in Canstatt's Jahresberieht (1852, Bd. i.) ; and by 

 Funke in Schmidt's Jahrbuecher (1851, p. 275.).] 



* At any rate the author's observations tend to 

 show that this is the case in Man and many 

 animals. Human gastric juice is stated by Dun- 

 glison (Physiology, vol. i. p. 503.) to smell of 

 hydrochloric acid. And Beaumont (p. 76.) asserts, 

 that it tastes like this acid in a state of dilution. 



f Beaumont, Op. cit. p. 72. 



J Loc. cit. pp. 183. et seq. 



