416 BOTANICAL GAZETTE [yUNE 
was first rapidly digested, the breaking down of the enzyme itself 
proceeding more slowly and continuing until complete. 
Solutions containing 12™ each of the impure enzyme were placed 
in the water-bath and kept at 40° C. for 12 days, the growth of bacteria 
being prevented by the addition of thymol. At short intervals, 
portions were removed and examined for digestion products by all » 
the methods employed in other experiments. Traces of peptones, 
leucin, and tyrosin were found after 14 hours, rapidly increased in 
amount for 10-14 hours, then very slowly increased for 9-10 days. 
During the first day, portions were hourly removed, filtered, and 
tested as to their activity upon egg-albumen, no perceptible decrease 
in power being shown. After the first day, portions were removed 
once or twice daily and tested, and there was found a decrease in 
power to digest egg-albumen proceeding pari passu with the increase 
of digestion products in the stock solution, until after the eighth day 
no perceptible action upon egg-albumen occurred, even after pro- 
longed standing. Contrary to my expectation, the process of auto- 
digestion was not checked or inhibited by the accumulation of its 
products, since it was equally rapid in the stock solution and in 
another from which the digestion products were daily removed. 
Furthermore, the two enzymes break down with equal rapidity, 
since activity in acid and alkaline media decreased equally until the 
eighth day, after which no action occurred. : 
No such decrease in activity occurred, nor were digestive products 
present, in purer preparations of the enzyme kept for a much longer 
period (five weeks) under similar conditions, nor were such solutions 
affected by light. 
It was hoped that a preparation purer than I had otherwise been 
able to make might be obtained by allowing the digestion to proceed 
until the associated proteid had been broken down, separating the 
products of digestion from the enzyme and drying the latter. To 
my surprise, digestion immediately began in aqueous solutions 
made from such a preparation, and would occur perceptibly in the 
moist precipitate while drying in a calcium chlorid desiccator. 
Autodigestion does not begin so long as there are present proteids, 
either egg-albumen, fibrin, or that present in the juice, but does begin 
as soon as these have been broken up. 
