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THE MICHIGAN ACADEMY OF SCIENCE. 



on comparison with the unaerated control. The comparison of the 

 paper aerated saliva and the unaerated control is shown in the follow- 

 ing table, the time indicated being that necessary to produce complete 

 inversion of the given quantity of the starch solution. 



TABLE II. 

 0.5 c. c. of 10 per cent saliva + 30 c. c. of 1 per cent starch solution at 37°. 



Thus the saliva has lost as the result of aeration over paper a portion 

 of its diastatic activity. It will be borne in mind that, in the case of 

 filtered saliva, with sufficient dilution, all the ptyalin can be removed. 

 So also we find that in the case of sufficiently diluted saliva, all the 

 ptyalin can be removed by aeration over paper. Thus a 2 per cent, 

 saliva aerated for three hours over paper, was found to be absolutely 

 inert when added to starch solution, whereas the corresponding control 

 produced complete inversion of the same quantit.y of starch under the 

 same conditions in fifty minutes. This one of several similar experiments 

 indicates the general trend of our results. The ptyalin is weakened in 

 activity (if the saliva is sufficiently dilute, entirely destroyed), by aera- 

 tion over paper, whereas similar side by side aeration over beads is with- 

 out effect. 



On taking the paper thus aerated with saliva, and washing until the 

 wash water no longer contains a trace of diastatic activity, and intro- 

 ducing this i^aper into starch solution, complete inversion of the starch 

 is produced, whereas control paper (perfectly fresh, hitherto unused 

 filter paper) produces no inverting effect whatever. Thus: 25 sq. cm. 

 of saliva aerated paper, on addition of 30 c.c. of 0.1 per cent, starch solu- 

 tion, produced complete inversion of the starch in 21/2 hours, while 25 

 sq. cm. of control paper produced no effect whatever on the same quan- 

 tity of starch in the same time. Test of the wash water showed it to 

 be completely inactive. 



Similar results were found to be the case without exception in numer- 

 ous repetitions of this experiment. 



Furthermore, on adding glycerin to the paper in the tube (after pre- 

 viously washing until the wash water no longer bears a trace of diastatic 

 activity) and aerating from one to twenty-four hours, the glyceri,n is 

 imparted a marked diastatic activity, whereas similar aeration with 

 water imparts to the water no such quality whatever. 



Experiment. — Tubes A and B were aerated side by side for twenty- 

 four hours with 10 per cent, saliva, and then washed until the wash 

 water Avas free from any trace of ptyalin. Water was then added to A 

 and glycerin to B, and again aerated for twenty-four hours. Tested 

 by adding 15 c.c of the water and of the glycerin to 15 c.c of 0.1 per 

 cent, starch solution respectively. Controlled with fresh water and 

 fresh glycerin. The table below gives the reaction of the mixtures to 

 iodine at the times indicated : 



