SOME PHYSICAL PROPERTIES OF PTYALIN. 



TABLE III. 



159 



Lack of activity of A is not due to destruction of the enzyme, as 

 a few shreds of the water washed paper after this aeration were found 

 to- produce complete inversion of 30 c.c. of 0.1 per cent, starch solution in 

 eighteen hours, whereas control papers were entirely inactive in an equal 

 length of time. 



Thus the glycerin really becomes a solution of ptyalin. 



The facts that ptyalin is removed from its solution by filtration 

 through hardened filter paper; that it is not removed by the Berkefeld 

 filter; that it is not affected by aeration over beads; that it is removed 

 from its solution by aeration over paper ; that this paper inverts starch ; 

 and that it yields a diastatic property to glycerin and not to water, 

 we take as demonstrating the fact that the ptyalin is fixed by hardened 

 filter paper. 



Enzymes have been generally believed to be quite iudialyzable or 

 dialvzable with great difBcultv. Gorsline, working in this laboratorv, 

 recently perfected a new method for making collodium sacs, and in view 

 of the very rapid dialysis of certain salts, he suggested the possibility 

 of the dialysis of enzymes through such sacs. We have shown that 

 ptj-alin possesses the property of readilv 

 dium sac. 



The sacs used in the demonstration 

 rotating the collodium sac tube twice 

 duced a verv thin sac 



dialyzing 



through 



of 

 in 



this property were made by 



dilute collodium. This pro- 



which collapsed when empty, was entirely 



areas, and was practically invisible when 



free 

 im- 



& 



from leaks or opaque 

 mersed in water. 



Seven collodium sacs were prepared in this manner, and each was 

 mounted on a glass tube with an air-tight joint obtained by constricting 

 the sac onto the tube over a small flame. In sacs 1 to G inclusive were 

 placed 5 c.c. of saliva, previously filtered through a single thickness df 

 ordinary filter paper. This filtrate was found to possess verj' great 

 diastatic activity. In the seventh sac, labeled ''C," were placed 5 c.c. 

 of the same saliva previously boiled for five minutes to destroy the 

 enzyme. This served as control. Each sac was then Immersed in a test 

 tube on foot, containing 20 c.c. of starch solution containing glycerin. 

 This starch on control test gave a deep blue coloration on the addition 

 of iodine. In no case did the liquid in the sac reach the joint, thereby 

 insuring the impossibility of the capillary escape of the saliva into 

 the surrounding liguid. The tubes were then placed in the incubator 



