474 BOTANICAL GAZETTE fe [DECEMBER 
small pieces of grape juice gelatin, in which the mycelium of the fungus was 
growing. Inoculation experiments with spores were not successful. The 
authors suggest that plants in nature may become infected through aphis 
punctures, the honey dew furnishing a means for the germination of the spores, 
or by means of frost injuries, or by accidental wounds made in picking the 
fruit. Since infection by any of these means was not demonstrated, and the 
authors’ own infection experiments with conidia were unsuccessful, these 
suggestions would be more convincing if supported by more experimentation 
and less theory. 
The disease produced by Cytesporina Ribis resembles in its general effects 
that caused by Botrytis. The infection takes place through a -wound, as is 
shown by the universal occurrence of an old scar or dead stump at the point 
from which the disease spreads. Cross-sections of infected branches show that 
the wood is brown and discolored except for a lighter sector-shaped area. The 
wood is permeated with hyphae which, unlike those of Botrytis, are able to 
. dissolve the lignified elements of the stem. The progress of the mycelium is 
accompanied by the formation of wound-gum which accumulates in the cells 
and vessels. The gum, at least in the wood parenchyma and medullary rays, 
appears to be formed from the starch. It seems that the accumulation of gum 
occurs only within the cells and does not involve the destruction of whole 
areas of tissues, as in most cases of gummosis. 
McALPINE™ reports a number of laboratory experiments with Phytoph- 
thora infestans, among which is an attempt to determine the possibility of 
destroying the mycelium in infected potato tubers without destroying the life 
of the tubers. Slices taken from diseased tubers were subjected to a tempera- 
ture of 49° for four hours, and the fungus was found to have been destroyed. 
Afterward seed potatoes were subjected to the same heat and were found to 
sprout freely, hence the conclusion that seed potatoes can be thoroughly dis- 
infected in the way described. It seems that the method should at least have 
been given a more extended trial to justify the conclusion, for it is not unlikely 
that wholt tubers would be injured if subjected to that temperature long enough 
to kill the mycelium in their interior, although the mycelium might be readily 
killed in thin slices. The author does not state whether the slices in which 
the mycelium was actually killed retained their vitality through the treatment 
ornot. Neither does he state that the seed potatggs used were diseased before 
the treatment and free from disease afterward —H. HASSELBRING. 
species of Penicillium and Aspergillus—The forms of Fungi imper- 
fecti grouped under the name Penicillium, on account of their omnivorous 
habits, have served as subjects for numerous physiological investigations, but 
as a rule little attention has been given to the determination of the species in 
* McAtpine, D., Some points of practical importance in connection with the life 
history stages Za ’ Phytophthora infestans (Mont.) DeBary. Ann. Myc. 8:156-166. 
pl. I. 1910. 
