7 o 4 
Journal of Agricultural Research 
Vol. XXIII, No. 9 
viously sterilized in small drops with a platinum loop and in considerable 
quantities by pouring it into the spike. Seven inoculations were made. 
Two only were successful, those in which the inoculum was applied by 
pouring. Isolations made from the infected spots produced typical 
Botrytis in pure culture. On May 24 a further ascospore inoculation was 
made. A potted plant was secured, the large interfering leaves were 
removed, and a half-grown inflorescence was sprayed with sterile water. 
An Erlenmeyer flask containing a large number of mature apothecia was 
now taken, the stopper was removed, and the resulting cloud of discharged 
ascospores was blown, with the aid of a rubber tube which had been 
immediately inserted into the flask, upon the wet spike, which undoubtedly 
caught thousands of them. The inflorescence was then covered in the 
usual way for 48 hours. On May 26 infection was evident on two or three 
male buds. One of them was removed and the surface sterilized, then 
used to inoculate a poured plate of agar, with a resulting development of 
Botrytis stage of Sclerotinia ricini. The inoculated spike was then cut 
from the plant and placed in a moist chamber. In three or four days a 
copious development of the typical gray mold occurred. (See PI. 3, C.) 
The writer was absent from the station during the month of June, and 
when he returned in July all his experimental plantings were scatteringly 
infected. This naturally made any further inoculations more or less 
uncertain, for it was impossible to determine in advance whether or not an 
apparently clean spike had been previously infected. However, early in 
September a few more ascospore inoculations were made, this time by 
placing well-developed apothecia directly into the sterilized and washed 
inflorescences in marked locations, holding them in place with paste and 
covering with waxed paper. Six cases out of 10 inoculated showed infec¬ 
tion after the usual two days, traceable apparently to the apothecia. Two 
showed infection appearing elsewhere than near the applied apothecia, 
and 2 out of 6 controls were infected. The results of these inoculations 
therefore would be more or less unreliable were it not for the fact that 
subsequent examination showed penetrating hyphae directly traceable to 
germinating ascospores. 
At this time also a considerable number of spikes were inoculated with 
conidia, and material was fixed at different periods for histological study. 
HISTOLOGICAL STUDIES 
It has been mentioned in various parts of this paper that materials were 
fixed and embedded for later histological work. The first consideration 
was to determine the manner of host penetration. A large amount of 
material was secured for this purpose, both from seedling inoculations at 
Cornell University, Ithaca, N. Y., and from field inoculations at Orlando, 
Fla. Material was fixed at different periods after spore inoculations in 
Fleming’s weak killing fluid. The different lots of material were washed 
and run up to 70 per cent alcohol in the field and held there for several 
months, then embedded in paraffin at Washington, D. C., during the 
winter of 1919-20. Several different kinds of differential stains were 
tried, but best results were secured with Pianeze IHb (21) and with 
Fleming’s triple stain. 
Early stages of penetration appeared to be practically identical with 
those pictured by Blackman and Welsford (1) for Botrytis cinerea. The 
leaves of plants grown in pure culture in 10-inch culture tubes on synthetic 
agar were inoculated by applying conidia thickly on the surface. Mate- 
