New YorK AGRICULTURAL EXPERIMENT STATION. 205 
As to the cytolytic enzyms, we are convinced that Green is 
right in his conclusion that these fall into two natural groups, 
the one active upon the pectic, and the other upon the cellulose 
elements of the cell membrane. Since both of these elements 
include a complex of chemical compounds we would naturally 
expect a corresponding variety to be shown in the enzyms 
which act upon them. There is, indeed, evidence that this 
does occur. The fuller understanding of the chemistry of the 
cell meinbranes must, however, precede such further subdivision 
of the enzyms acting upon each. For the present we can at 
least accept the following as representing well-defined groups 
of components in the simpler or less modified plant tissues: 
1. True celluloses. 2. Hemicelluloses. 3. Pectic compounds. 
In the more modified tissues there are other compound cellu- 
loses, ligno-cellulose, etc., which do not here concern us. 
Evidence is not lacking that there are enzyms capable of 
hydrolyzing the true celluloses, but further study is necessary 
before their relationships can be defined. The cytolytic en- 
zyms, which have been studied in sufficient detail so that we 
can characterize them, act only upon the last two of these 
three classes. As already indicated, we consider these enzyms 
to be as clearly separable into two groups or kinds as are 
the wall elements upon which they act, and we believe it must 
conduce to clearness of understanding if a distinct name be 
accepted and defined for each of these kinds of enzym. 
The enzym of B. carotovorus and the related soft-rot bac- 
teria is a good example of one acting upon the pectic com- 
pounds, but not hydrolyzing the hemicelluloses. Such anenzym 
has heretofore been referred to usually as “cytase.” If the 
cytolytic enzyms are to be differentiated some more specific 
name must be found. Following the custom of naming enzyms, 
pectase would be the right name had it not been applied to 
Fremy’s ¢lotting enzym. If one accepts the grouping of the 
celluloses outlined by Cross and Bevan and: considers these 
pectic elements of the wall to occur in compound with cellulose 
or pecto-celluloses preference might be given to the name pecto- 
