R. H. Chittenden — Ferments of Pineapple Juice. 293 



later show that the proteolytic ferment is either preeipitable by heat, 

 or else is associated with proteid bodies so precipitated. Now since 

 the total amount of matter preeipitable by boiling from 100*^'^ of 

 filtered pineapple juice amounts to only 27 milligrams, and this obvi- 

 ously cannot be all j)roteo]ytic ferment, it is probable that the 

 amount of pui'e ferment contained in the quantity of pineapple 

 juice used in the various digestions recorded does not amount to 

 more than a few milligrams, and yet in one experiment with the 

 above quantity of ferment the equivalent of 1714 milligrams of dry 

 muscle proteids were dissolved in one hour at 40° C, and of blood 

 fibrin an amount equivalent to 1283 milligrams of dry proteid in two 

 hours at 40° C. 



With such vigorous digestive action as this, many possibilities 

 suggest themselves in the way of practical application of the isolated 

 ferment, or even of the pineapple juice itself. As a means of pep- 

 tonizing foods it offers peculiar advantages in that the products of 

 digestion, to be referred to later, are free from the objectionable 

 taste usually associated with peptones resulting from the proteolytic 

 action of animal ferments. Again, the ferment cannot but consti- 

 tute a good solvent for pseudo-membranes, while its vegetable origin 

 would perhaps recommend it as a more agreeable remedy than the 

 kindred ferments from animal tissue. In some sections, popular 

 opinion has already accredited to pineapple juice virtue as a sol- 

 vent for the false membranes formed in diphtheria, a belief which 

 is now seen to be founded on a reliable basis. 



2. — Influence of temperature. 



It is a matter of common observation that the digestive ferments, 

 or enzymes, present in the animal organism act most energetically 

 at approximately the body temperature, viz: 38°-40° C. Certain of 

 the vegetable ferments on the other hand, notably the diastase of 

 malt, act most vigorously at a higher temperature. With papain, 

 the proteolytic ferment of papaw juice, Martin demonstrated the 

 greater activity of the ferment at temperatures between 30° and 

 36° C. than between 18° and 20° C. in neutral solutions,* but appar- 

 ently the effect of higher temperatures was not tried. 



Experiment XI. — The 10 grams of moist albumin coagulum used 

 in the digestions contained 1*4990 grams of dry albumin. The 

 several mixtures were warmed with the albumin at the stated tem- 



* Journal of Physiology, vol. v, jx 221. 



