1900] BOTRYTIS AND SCLEROTINIA 381 
which showed this type of thé disease in its purest form, or cul- 
tures made from them, it was found that when bits of diseased 
tissue were buried in the soil beside healthy plants, or inserted 
in cuts in the stem, the disease was at once produced. It was 
further found that if affected plants or portions of them were 
buried in a flower pot and lettuce plants set in, the latter would 
soon begin to die off and all eventually succumb, the mycelium 
soon appearing upon the surface of the soil in the characteristic 
manner. With sclerotia, pure mycelium, or pieces of sclerotia, 
the same results are obtained. In noneof the experiments were 
the plants covered or placed under any conditions different from 
those of ordinary greenhouse culture. These results show 
plainly that this species or form is an active parasite, capable of 
causing the disease in the most vigorous plants at any age, but 
at the same time able to flourish under purely saprophytic condi- 
tions. It is likewise able to reproduce itself from year to year 
indefinitely by purely vegetative development, forming freely, 
either as a saprophyte or parasite, sclerotia which are able to 
Survive all ordinary conditions? and produce the fungus anew. 
It would seem, in fact, that this is the only method of reproduc- 
Mon of this form. The results of sterilizing the soil have 
been already alluded to. It was found that when not less than 
three inches of the surface soil had been steam sterilized not a 
plant was affected, even in the worst infested beds. The only 
€xception to this was the one crop where the pure botrytis type 
Occurred, Plainly, therefore, the no-botrytis form depends very 
largely, if not entirely, upon saprophytic growth in the soil 
and the sclerotial resting stage for the continuance of its 
existence, 
THE LARGE SCLEROTIA TYPE. 
In a lot of lettuce plants sent by a gardener in eastern Mass- 
achusetts a third type of the “drop” was found. In this case 
the general nature of the disease was typical, and the parasitic 
* Many results that relate to the biology of these forms are omitted here as they do 
not bear on the present : ubject. 
