376 BOTANICAL GAZETTE [JUNE 
* 
case of belated “damping off,” made possible by the weakened 
condition of the plants. 
Cultures made from affected tissue from these plants and 
from the Botrytis conidia gave similar results. A rather scanty 
mycelium developed, bearing numerous organs of attachment and 
but few conidia. Often no spores developed until after several 
weeks, even in cultures made directly from conidia. Compared 
with cultures made from ordinary saprophytic Botrytis vulgaris, 
these seemed to show that as the fungus takes on a parasitic 
nature it produces fewer conidia and more organs of attachment, 
though it is extremely variable and uncertain in these respects. 
Sclerotia were sparingly produced in almost all cultures made 
from this material. These appeared first as reddish, blister-like 
elevations in the substratum, gradually becoming black and hard. 
They were mostly longer than broad, thin, firmly attached to the 
substratum and inseparable from it. Test fig. z f shows some of 
these sclerotia grown on gelatine, portions of which are still 
attached to them. The photograph does not bring out clearly 
the size and form of the single specimens, as it is impossible to 
Separate them cleanly. Thus, “zt jig. 1 f* is a piece of gelatine 
having on its surface two long, thin, narrow sclerotia lying parallel 
to one another, while /» consists of several sclerotia with more 
or less gelatine. Fig. 44 also represents some of these forms, 
but fails to bring out their thinness. If placed in wet sand soon 
after being formed these sclerotia produced an abundant crop of 
Botrytis conidiophores and conidia. The ability to produce 
conidia appeared to be lost with age, and after a few months 
drying the development was largely of mycelium, though this 
was rather scanty. 
In order to determine still more fully the relation of Botrytis 
to the lettuce disease some investigations were made along the 
line of infection experiments. Humphrey reports such to have 
been unsuccessful. Experiments on early mature lettuce plants 
gave the following results. 
I. Pieces of affected plants buried in the soil beside healthy 
plants generally produced the disease. 
