262 Chittenden and Hutchinson—Influence of A 
portion of 1:5. _ Hence, each digestive mixture contained 2 ¢.¢. of | 
undiluted saliva, 
The amount of reducing substances, which for the sake of conven- 
ience are calculated as dextrose, were, as already mentioned, deter- 
mined volumetrically and from the data so obtained, the percentage 
of starch converted was likewise calculated. 
Uranyl nitrate. 
With this salt the following results were obtained : 
{ 
Total amount Relative 
U0.(NO3)2+6H20. reducing bodies. Starch converted. amylolytic action. 
0 0-4135 gram. 37°21 per cent. 100-0 7 
0:0001 per cent. — 0-4083 36°74 98°7 ; 
0:0003 0°3873 34°85 93.6 
00005 0°3698 33°28 89°4 
0-001 0°3612 32°50 87°3 
0-008 0°3131 28°17 75°5 
The inhibitory action of the uranyl salt is plainly manifest in 
these results. A second series of experiments, with still larger per- 
centages of uranyl nitrate, show the retarding action still more 
plainly. 
Total amount Relative 
UO.(NOs3)2+6H20. reducing bodies. Starch converted. amylolytic action. 
0 0-4066 gram. 36°59 per cent. 100-0 
0-001 per cent. 0:4000 36°00 98°3 
0-002 03880 34°92 95°4 
0-008 03034 27°30 74:6 
0-004 02545 22°90 62°5 
0-005 0-1550 13°99 38°2 
0-008 trace. 
The largest percentage of the salt used (0°008 per cent.), is seen to 
almost entirely prevent the action of the ferment, thus showing how 
extremely sensitive the salivary ferment is to the action of this salt. 
Comparing the two series of experiments, it is seen further, that a 
given percentage of the salt, say 0°001 per cent., is much more active 
in one case than in the other, indicating that the action of the salt is 
not constant. This is undoubtedly true to a limited extent. The 
action of a given percentage of the salt is constant only under like 
conditions. In the above series of experiments, the saliva is different 
in the two cases, and the real explanation of the difference in action 
is to be sought for in the amount of proteid matter contained in the 
saliva. Undoubtedly the retarding action of the uranium salt is 
checked, in part at least, like that of mercuric chloride,* by the 
* Studies from this Laboratory, 1884-85, p. 71. 
' 
