Chittenden and Smith — Diastatic Action of Saliva. .357 



period of digestion ; still, the amount of starch converted is 

 increased on an average about 1 -50 per cent. It is interesting to 

 note that under these conditions the full effect of the proteid matter 

 is produced by even 0*05 per cent. Langley and Eves found the 

 maximum effect with saliva ten times diluted to be produced by 

 about O-l per cent, peptone. In our experiment, however, the dilu- 

 tion of the saliva in the digestive mixture is 1 : 50. 



Influence of proteid matter on the diastatic action, of saliva in 



alkaline solutions. 



It was previously demonstrated by one of us that the presence of 

 1 per cent, peptone in a digestive mixture containing 25 per cent, 

 saliva and 0-3 and 0-15 per cent, sodium carbonate respectively, tended 

 to nearly double the diastatic action, bringing it up almost to the 

 action of saliva unmixed with alkaline carbonate. 



We give here a few additional experiments bearing on this point. 



The very noticeable difference in the action of small percentages 

 of sodium carbonate on the diastatic activity of moderately dilute 

 and very dilute saliva at once suggests the possibility of some con- 

 nection between the dilution and the reduced percentage of proteid 

 matter. What, now, is the influence of small amounts of peptone 

 on very weak alkaline solutions of saliva ? We will give the 

 I'esults of one series of experiments in answer to this question. 



Series XII. 

 20 c.c. of saliva with an alkalinity equal to 0"110 per cent, sodium 

 carbonate were diluted to 100 c.c, 10 c.c. of the diluted saliva were 

 used in each digestion of 100 c.c; consequently the alkalinity of the 

 digestive mixture was equal to 0*0022 per cent, sodium carbonate. 

 Neutral peptone was added in varying quantities. The mixtures 

 were warmed at 40° C. for 30 minutes. 



The same saliva neutralized converted 30*61 per cent, of the starch 

 into sugar; consequently the neutral peptone (0"2 per cent.) caused 

 the alkaline saliva to show a diastatic action considerably greater 

 than the neutral saliva, but not equal in this case to the action of the 

 same percentage of peptone on the neutralized saliva. Compare 

 series xi, made with the same saliva. 



