[Vor. 1 
316 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
that these two fungi are capable of producing pectinase. The 
cultures were kept at a temperature of 18-20?C. 
Experiments with calcium pectinate.—Caleium pectinate was 
prepared by treating a water solution of pectin with freshly- 
made limewater (care being exercised to avoid an excess of lime), 
the product thus obtained being filtered off and thoroughly 
washed until it was no longer alkaline. The calcium pectinate 
thus prepared was used in making a pectinate agar in a manner 
similar to that employed in the preparation of cellulose agar, 
the same mineral nutrient solution (nutrient A) being used and 
the whole rendered sterile by fractional sterilization. After 
the last heating, care was taken to distribute the pectinate, 
which quickly settles to the bottom of the tubes, uniformly 
throughout the agar by stirring the medium with a sterile glass 
rod. These tubes were then inoculated with Sclerotinia and 
with Penicillium, the object being to compare the action 
toward pectic substances of two fungi that have entirely dif- 
ferent effects on the host cells, the former producing no soften- 
ing effects, while the latter causes a very rapid softening and 
disorganization of the host tissue. 
The inoculated tubes of pectinate agar prepared by the above 
method were kept at a temperature of 22-24°C. Contrary 
to expectations, there was very little growth when no soluble 
carbohydrate was supplied, and, furthermore, no dissolving 
action on the calcium pectinate. On the other hand, when 0.5 
per cent glucose was added, both fungi produced a vigorous 
growth, but neither one gave any indication of pectinate hydroly- 
sis, or dissolution. Here again, as in the cellulose hydrolysis, 
the two fungi, Sclerotinia and Penicillium, behave alike. This 
is not in accordance with the observed behavior of these two 
organisms toward the host tissue. 
ACID RELATIONS OF THE FUNGUS 
Some investigators have held that the content of tannin (47) 
and of malic and other acids of the host determines whether or 
not the fungus can grow in the tissues and rot the fruit. In 
accordance with this view a fungus may not so readily attack 
green as ripe fruit, the former being supposed to exhibit a higher 
