ut рр 
Bui? 
1914] 
COOLEY—SCLEROTINIA CINEREA 313 
uting this action of the enzyme to the presence of calcium salts. 
It is of interest to note that pectase was one of the first plant 
enzymes to be described. Bertrand and Mallévre (7, 8) con- 
cluded that pectose and pectase are almost universally present 
in green plants, being especially abundant in the leaves. These 
authors showed that acidity is an important factor in the inhi- 
bition of coagulation of pectie bodies by pectase, and also that 
either barium, calcium, or strontium is necessary for the action 
of pectase. 
Mangin (35, 36), by mieroscopie tests, has thrown much 
light on the nature of the middle lamella and holds that pectose 
is very pronounced in the cell walls of young tissue. In the 
older cell walls, on the other hand, this author believes that 
calcium pectate predominates in the middle lamella, considering 
that the latter is largely if not entirely composed of this sub- 
stance and that it frequently collects on the surface of the cell 
walls adjoining intercellular spaces. Bourquelot (11), and 
Bourquelot and Hérissey (12) secured a thermo-labile enzyme 
from barley malt extract which acted upon a solution of pectin 
(taken from the gentian root), changing the latter in such a 
way that it was no longer coagulated by pectase. The action 
of this enzyme, which they called pectinase, was thought by 
them to be that of converting the pectin into reducing sugar. 
They also designated as pectinase an enzyme which dissolves the 
pectic coagulum (the latter has been supposed to be calcium 
pectate). A good resumé of the status of the chemistry of 
pectic substances is given by Bigelow and others (10). 
A number of investigators have reported upon the action 
of bacteria on plant cells, including the effects of the organisms 
on the middle lamella. Winogradsky (55), Behrens (5), and 
others attributed the changes taking place in the flax plant dur- 
ing retting to the dissolving action which the bacteria exert on 
the middle lamella. It will be unnecessary to review here any 
more of the earlier work which has been done along this line, 
since it has been so thoroughly discussed in the comprehensive 
publications by Jones (29), and Jones, Harding, and Morse 
(30) on the soft rot of vegetables. These authors studied the 
effect of the soft-rot bacillus (Bacillus carotovorus) on the host 
and find that the organism is identical with what has been 
