412 BOTANICAL GAZETTE [JUNE 
able by proper treatment. Some experiments with this purpose in 
view met with partial success. 
A neutral solution of one gram of the dry enzyme in 100° water 
was carefully heated to 65° C. Upon gradual addition of NaCl 
crystals a slight precipitate settled out, which when collected by 
filtering, and dried, weighed 0.31%". The filtered liquid when 
freed from NaCl showed no activity upon egg-albumen in acid 
solutions, regardless of strength, but its activity in alkaline solutions 
was undiminished and accorded in all respects with that of ordinary 
preparations of the enzyme in alkaline media, the products of diges- 
tion with the two being identical. The heat precipitate was imper- 
fectly soluble in water and showed no action upon egg-albumen in 
any medium. 
I believe that these facts, with the differences, elsewhere stated, 
in the action of poisons upon acid and alkaline solutions of the enzyme, 
justify the conclusion that there are present in the preparation two 
enzymes, one active in acid, the other in alkaline solutions. J am 
aware that full proof of this statement demands isolation of the acid- 
enzyme without destroying it in the process, but this I am as yet 
unable to do. | ’ 
That the presence of NaCl is a necessary condition for the pre- 
cipitation of the acid-enzyme is shown by the fact that no precipitation 
occurs in unsalted solutions until heated to 76° C., activity in both 
acid and alkaline media being retained until complete precipitation 
occurs at 87-90%. 
EXPERIMENTS WITH POISONS. 
In the experiments with poisons, solutions containing o.006*™ 
of the enzyme per cubic centimeter were made up with distilled 
water previously made acid or alkaline by the addition of HCl or 
NaOH. An m/32 acid or alkali was adopted as a medium for all 
digestions, since this strength allowed optimum activity in each case. 
Thymol was used to prevent bacterial infection and was found per- 
fectly satisfactory. Of this solution 5°°, containing 0.03%™ of the 
enzyme, were transferred to each of the test-tubes to be used. To 
each was then added 5°¢ of the poison to be used, of twice the desired 
strength, 7. e., 5°° enzyme solution plus 5°° m/so000 Ba(NO,), gives 
