130 
AMERICAN JOURNAL OF BOTANY 
[Vol. io, 
and 48 hours, respectively, to complete maceration. A comparison of 
these two species when grown at 9 0 and 20° shows a decided decrease in the 
amount of pectinase produced at the lower temperature, although both 
are relatively low-temperature forms. The losses caused by the latter 
species frequently occur at a temperature not much higher than the lowest 
temperature used in these experiments. The tissues of potatoes decayed 
by nigricans under storage conditions are completely disintegrated, and 
the middle lamellae are dissolved out so that coherence is entirely lost, 
a fact which suggests that a pectinase is produced. Furthermore, the 
decay is rapid, and the dissolution of the middle lamellae takes place con¬ 
siderably in advance of the growth of the hyphae. 
A study of the data derived from the use of the mycelium shows some 
interesting facts. It should be pointed out in this connection that the 
rapidities of maceration by the enzym in the solution and in the mycelium 
are not strictly comparable, since no attempt was made to use a quantity 
of enzym powder that would be equivalent in macerating power to the 
enzym contained in the solution. It will be seen that the mycelium of 
oryzae , delemar , and chinensis grown at 40° C. contained a small amount 
of enzym. Microsporus , one of the nonparasitic species, produced a small 
amount at 20° and at 9 0 . A comparison by this method of chinensis and 
microsporus with nigricans , a species which readily decays potatoes at 20° 
or lower, indicates that the latter produces a smaller amount of the macer¬ 
ating principle. The comparison of the results obtained with microsporus 
and nigricans in the solution at the same temperature shows similar results. 
There are some outstanding differences between the results obtained with 
the solution and those obtained with the mycelium. It has been pointed 
out that the amount of enzym in the solution increased with the decrease 
of temperature from 40° to 20°, and then decreased when the temperature 
was lowered to 9 0 . On the other hand, results obtained from the mycelium 
did not follow the same general course when the temperature was lowered 
from 20 0 to 9 0 . As a matter of fact, the results here show that, with one 
or two exceptions, there is more pectinase in the mycelium grown at 9 0 than 
in that grown at 20°. It is interesting to note in this connection that Harter 
(4) found amylase to be present in larger amount in the mycelium of R. 
tritici grown at 9 0 C. than at any higher temperature tried up to 40° C. 
On the whole, the results show that a larger amount of pectinase is produced 
per unit measure at intermediate to relatively low temperatures than at 
high ones. In two cases in which mycelium was used, chinensis at 40° and 
nigricans at 20°, the results are recorded in the table as varying from 8 to 
24 hours. This merely means that some maceration had started in 8 hours, 
and that the process was completed in 24 hours, no further examination 
of the material having been made. 
The results of these investigations show that, at least within the limits 
of these experiments, pectinase is produced at any temperature at which 
the organism grows. The amount produced is least at the higher and most 
