284 
F. A. Wolf, 
originally isolated from Egg plants. A fungus, to all appearances iden¬ 
tical with the Potato- and Egg plant -Rhizictonia, has also been isolated 
from green Tomato fruits. Rolfs (6) has previously reported, on 
Tomatoes, an organism which agrees quite well, in size and shape of 
the spores and the structure of the hyphae with the Corticium of the 
Potato. An unidentified Rhizoctonia has also been observed on 
Tomato fruits in Nebraska(19). More recently Wollenweber (;3) has 
noted a form, Rhizoctonia potomacensis , Wr. which is productive of a 
fruit rot of Tomatoes. This species differs from R. Solani in the 
character of its attack in that concentric, subepidermal mycelial zones are 
formed within the Tomatoes 1 ). The successful inoculation of Egg plants, 
by the writer, with the form isolated from Tomatoes furnishes conclusive 
proof that it is also physiologically identical with the form originally iso¬ 
lated from Egg plants and from Potatoes. 
II. Occurrence of an enzyme and its isolation. 
Because of the fact that tissues were observed to be decayed, as 
has been noted before, in advance of the fungus, the idea was suggested 
that the decay must be due to enzymotic activity and that the enzyme 
is either activated by 
the presence of the 
fungus within the 
tissues of the fruit 
or is itself a secre¬ 
tory product of the 
fungus. The problem 
was then to deter¬ 
mine the presence of 
an enzyme, its origin, 
and the manner in 
which it affects living 
tissues. In order to 
do this attempts were 
simultaneously made 
to extract an enzyme 
from ripe, healthy 
fruits, from decaying 
fruits, and from the mycelium itself. Since the fungus can be made 
to produce a luxuriant superficial growth of mycelium in a humid 
atmosphere, no difficulty was experienced in securing twenty grams of 
this mycelium. This was macerated in a mortar, sixty cubic centimeters 
of distilled water were added, and the whole was allowed to stand for 
six hours. By means of a press forty-six cubic centimeters of liquid were 
recovered from the twenty grams of mycelium together with the sixty 
cubic centimeters of water. An extract from ripe fruits and decaying 
fruits was obtained in much the same way. 362 grams of ripe Egg plants 
were first ground through a meat chopper, were then further macerated 
1) „Von Rhizoctonia potomacensis unterscheidet sich diese ( R . Solani) durch das 
Krankheitshild an Tomate, das auffällige suhepiderinale concentrische Mycelzonen 
zeigt, die R. Solani fehlen“; 1. c. p. 30. 
Fig. 4. a C h 1 a m y d o s p o r e s r of Rhizoctonia on Egg plants ; 
— b Mycelium showing characteristic method of branching 
and septation (enlarge 300 x). 
