P68 Report OF THE BOTANICAL DEPARTMENT OF THE 
sketch. They originate from a very extensive, much branched 
brownish subepidermal mycelium and a much less profuse 
cortical mycelium. Both longitudinal and cross sections show 
the mycelium rather abundant in the cortical regions, but the 
deeper tissue reveals none except in cases where there is a 
wide gap in the sclerenchyma tissue, and even in such cases it 
does not progress very far between the bundles till some time 
after the maturity of the Diplodina spores. There were some 
cases noted in the greenhouse where the vines were killed about 
the time the spores were mature. Sections of such vines had 
abundant mycelium even in the pith region. A few days after 
such a vine had been killed by the disease a photograph was 
made of its cross section which clears up some points. See 
Plate X. 
Discharge of pycnidiosporcs and how the disease was spread. 
—Upon examination of the pycnidia with a hand lens the 
darker ones are all seen to have papillate elevations in place of 
pore-like ostiola. By the addition of a little water to some 
unbroken pycnidia under a cover glass the microscope showed 
the papillate elevations to be masses of two-celled hyaline 
spores which had been forced out from the interior of the pye- 
nidia. Shortly, the masses loosened somewhat showing indi- 
vidual spores more clearly, streamed off into the water, with a 
rather compact column of like spores continuing the stream- 
ing as long as three or four minutes. If one now recalls that 
this fungous disease was preceded by an attack of red spider and | 
then followed by a long daily siege of heavy spraying with 
hydrant water, it will probably help explain the rapid spread 
of the disease after it had once started. And it also seems 
probable that an explanation of the position, on the vine, of 
all infections may be sought here. During spraying the pye- 
nidia were moistened and those having mature spores would 
send forth numerous streams of spore masses which were at 
once carried away by the continuous stream of water and 
lodged on other vines, even at some distance beyond, down 
which they would be washed by the descending water. As 
the axils of leaves and the crotches of branches would natu- 
