1900 | BOTRYTIS AND SCLEROTINIA 379 
to its treatment. Were this the only form to occur it would 
cause little trouble in the Boston district, as it is almost unknown 
there except for an occasional case of “ black root.” 
THE NO-BOTRYTIS ty Pr, 
Among all the cases of the disease examined by the writer, 
those inwhich Botrytis appeared have been by far the exception. 
In the type of the disease most prevalent in Massachusetts no 
conidial form whatever can be found. In its general effect the 
disease is entirely similar to that already described and indistin- 
guishable from it. Affected plants wilt and collapse and in a few 
days are entirely destroyed. The usual mycelium is found in 
the stem. It is also usual to find an abundant, white, woolly 
mycelium proceeding from affected plants to the surrounding 
soil where it flourishes luxuriantly for a time, often spreading to 
and attacking adjacent plants. In fact it is evident that what- 
ever form of reproduction this fungus may possess its principal 
mode of spreading in the greenhouse is by growth in the soil. 
Wherever one plant is attacked the neighboring ones almost 
always follow, and the mycelium grows luxuriantly upon the 
soil, extending from plant to plant. On coming into contact 
With a healthy leaf it spreads over the surface, forming numerous 
organs of attachment (fig. 37). Fig. 29 shows in cross section 
the result of this, the epidermis breaking down and the fila- 
ments penetrating and destroying the leaf. Sclerotia are formed 
in considerable abundance on affected plants, especially on the 
stem and beneath the leaves, but they are very small and easily 
°verlooked in the soil. Cultures are easily made with bits of 
affected tissue or mycelium, and hundreds have been made in 
this Way with no sign of Botrytis. Such cultures produce a con- 
siderable mycelium, more abundant on bread than on gelatine, 
and very numerous sclerotia. This mycelium is composed of fila- 
ments indistinguishable from those in the botrytis form. Organs 
of attachment are numerous and entirely similar. The sclerotia 
are very small, mostly about the size of a pin head. Some are 
a little larger, but thin and irregular in shape, while often a sort 
