ACTION OF THE GASTRIC JTJICE ON FATS. 267 



These facts, showing that something more is necessary in 

 stomach-digestion than mere solution, point to pepsin as 

 the important active principle in producing the peculiar 

 modifications so necessary to proper assimilation of nitro- 

 genized alimentary substances. The action which takes 

 place is one of those ordinarily termed catalytic, in which 

 the pepsin, acting by its mere presence, as a ferment, induces 

 these peculiar changes. 1 They are, however, an essential, 

 and the most important part of the action of the gastric juice, 

 and the transformation into albumin ose takes place in all 

 nitrogenized principles which are liquefied in the stomach. 

 As it is impossible for two catalytic processes to take place 

 at the same time in any single organic substance, the more 

 powerful always overcoming and taking the place of the 

 weaker, it is evident that when nitrogenized principles in 

 process of putrefaction are introduced into the stomach, the 

 catalytic process of putrefaction must cease when the 

 changes which take place in digestion become established. 

 This explains the antiseptic properties of the gastric juice, 

 and the frequent innocuousness of animal substances in va- 

 rious stages of decomposition taken into the stomach. 



Action of the Gastric Juice on Fats. Beaumont does 

 not say much with regard to the changes which fatty sub- 

 stances undergo in the stomach, except that they " are di- 

 gested with great difficulty." 2 All the recent observations 

 on this subject show that these principles, when taken in the 

 condition of oil, pass out at the pylorus unchanged. Most 



recognized in the urine. In a subsequent account by Bernard of experiments on 

 the injection of albumen into the circulation (Liquides de V Organisrne, Paris, 

 1859, tome ii., p. 459), there is no mention of the effects of injecting albumen 

 dissolved in the gastric juice, though the first experiments upon the injection of 

 pure albumen are confirmed. The facts are nevertheless interesting and instruc- 

 tive, as showing the want of assimilation of undigested nitrogenized principles 

 mixed with the blood. 



1 For a definition of the process of catalysis, see vol. i., p. 74. 



2 Op. cit., p. 45. 



