Range of Action of Digestive Ferments. 101 



there may be found a variable amount of acid (kydrO' 

 chloric acid), according to the stage and activity of 

 digestion, and the character of the food ; but there is good 

 reason to suppose that it readily reaches the proportion of 



1 part in 500 of the mixed contents of the stomach. A 

 considerable time, as much as three or four hours, may elapse 

 before the extreme degree of acidity is reached ; but there 

 can be no doubt, after the observations of Beaumont and 

 others, that an intensely acid secretion is poured out as soon 

 as the lining membrane of the stomach is stimulated by the 

 contact of food. 



The first series of experiments consisted in heating a 

 mucilage of 10 grains of arrowroot in 20 cubic centimetres 

 of water, for two hours, at 95° F., under different conditions as 

 regards reaction and presence or absence of the ferment : — 



I. Mucilage heated alone for two hours, still remained 

 thick, and would not filter. 



TI. Mucilage heated, as above, with addition of 2 grains 

 each of zymine and bicarbonate of soda. In a few minutes 

 there was distinct thinning of the mixture, which at the end 

 of the time was quite liquid, and filtered easily. 



I IT. Mucilage, with 2 grains of zymine only. The result 

 was the same as in No. II., though the mixture had a very 

 slight acid reaction. 



IV. Mucilage, with xoioo P^^'t of hydrochloric acid, and 



2 grains of zymine, 



V. The same, but goVo P^^^ of acid. 



VI. The same, but xouo P^^^^ of acid. 



Even with No. IV., there was some retardation of the 

 solvent action, while with No. V., and still more with 

 No. VI., there was a considerable amount of the swollen 

 starch left in clotty pieces at the end of two hours. 



VII. and VIII. To test this efifect further, and with 

 reference both to the amylolytic and tryptic elements in the 

 mixed ferment, 10 grains of zymine were heated for two 

 hours at 95° F., in 40 c. ctrs. of water, containing xoW part 

 of hydrochloric acid. The mixture was then divided into 

 two equal parts, to one of which was added pressed fibrin, 

 10 grains, and to the other, 10 grains of starch boiled in 

 20 c. cs. of water. Each of these was again kept for a full 



M 



