17 
as possible, were rubbed with sand to a fine pulp and the juices pressed 
out. A portion of each of these juices was kept separate as control, 
while the chief portions were mixed with an equal volume of @ solution 
of albumin. This solution was obtained by pressing the white of an 
egg through linen, diluting the liquid with fifteen times its bulk of 
water and filtering. A portion of the albumin solution was also diluted 
with an equal volume of water and kept for control. All liquids were 
kept at from 18° to 22° C. in closed test tubes which had received an 
addition of ether to exclude bacterial development. After nine days 
the filtered liquid received an addition of some nitric acid and the pre- 
cipitate formed was left one day to settle. The volume of the precipi- 
tate showed a moderate decrease in the juice of the fresh leaves and a 
considerable decrease (about one-half) in that of the starved leaves; 
therefore the existence of a proteolytic enzym can not be doubted, but 
it differs from the ordinary trypsin, inasmuch as it can not attack 
fibrin and casein under ordinary conditions, while it can attack dis- 
solved albumin. 
As to the first-mentioned control cases of the juices which had not 
received the addition of egg albumin, the soluble albumin originally 
present as reserve matter in the juice was found fully digested in the 
juice of the starved, but not yet completely so in that of the fresh 
leaves. 
IS A CELLULOSE-DISSOLVING ENZYM (CYTASE) PRESENT IN TOBACCO 
LEAVES? 
Cytohydrolytic enzyms, especially such as easily attack hemicellu- 
loses, occur in phanerogamous plants and are not identical with 
diastase, as Newcombe! has demonstrated. He found such an enzym 
in the cotyledons of seedlings of Phoenix dactylifera and of Lupinus 
albus and confirmed its presence in the malt of Hordeum vulgare. 
Parasitic fungi, such as eat through wood, must contain enzyms 
which dissolve the genuine cellulose with great facility. Various 
observations, especially those of Dr. Erwin F. Smith on bacteria acting 
aS plant parasites, leave no doubt as to the occurrence of such enzyms 
also in certain species of bacteria. 
The fact that tobacco leaves lose more or less of their original degree 
of tenacity and cohesion, and even show holes when subjected to 
Sweating in a too moist condition, appears to find a simple explanation 
in the action of bacteria, which may occur in the presence of too much 
moisture. But it would have to be assumed that cellulose dissolving 
bacteria, of which not many kinds are known, are always present 
whenever too much water is applied to the tobacco. It was therefore 
of interest to test whether cytase, which has been shown to be present 
in certain germinating seeds, was also contained in the tobacco leaf 
itself, or whether it was eventually formed from another enzym in the 
“l Annals of Botany, March, 1899. _ 
20914—No. 65 2 
