1900] BOTRYTIS AND SCLEROTINIA 375 
seem remarkable, therefore, for so similar a disease as the 
“drop” to be caused by the same fungus. But of course the 
occurrence of this so common species upon affected plants 
comes far from proving it to be the parasite, and especially since 
many cases of the typical disease occur where no trace whatever 
of this fungus, or at least of its conidial form, can be found, 
Humphrey’s conclusions cannot be accepted without further and 
more definite proof. The most convincing case in this respect 
seen by the writer was that of a crop of lettuce grown in one of 
the station greenhouses in the winter of 1898-9. The ‘‘drop” 
had been introduced into this house for purposes of study in 1897 
and had been abundant in each crop since then. In no case, 
however, had any Botrytis appeared. Meantime, a method of 
treatment had been developed by which this no-botrytis type of 
the disease was completely held in check. The treatment con- 
Sisted in sterilizing the soil by means of steam, and crop after 
Crop was grown, with or without the disease at will. When this 
crop was set out the plants were overgrown and “‘spindling,” 
having been too long in the flats. Consequently the outer leaves 
died off and the plants received a severe set back. Added to 
this the house was not properly ventilated and on several occasions 
the temperature was much too high. Soon after being set out the 
plants began to ‘‘drop,” and in a few weeks the majority of 
them, in treated and untreated soil alike, were gone. Affected 
plants showed a mycelium in the stem indistinguishable from 
that in all other cases. Organs of attachment occurred as usual. 
Botrytis was abundant on every plant, especially when kept over 
night in a moist chamber. No mycelium was visible upon the 
Surface of affected plants nor did it spread to the surrounding 
Soil, and it could not be seen that the disease spread from plant 
to plant. The leaves were scarcely or not at all affected except 
at the very base and the rotting was almost entirely confined to 
the stem, the rest of the plant drying up. There is no reason to 
doubt that these plants were affected primarily with Botrytis 
vulgaris, originating presumably from conidia in the air, and such 
1s believed to have been the case. It appeared to be essentially a 
