Pilzkrankheiten der Pflanzen 
291 
Fusarium culmorum W. G. Sm. were found to be parasitic when under 
favorable conditions they came in contact with seeds and seedlings. Clado- 
sporium gramineum Cda. and an undetermined species of Alternaria 
are not parasitic under the conditions used in the experiments. Pure cul- 
tures were used in tlie experimentation in whicli the plants were grown 
in pots and in the field. F. A. Wolf (Auburn, Ala.). 
JACKSON, H. S., A new pomaceous Rust of economic iniportance, 
Gymnosporangium Blasdaleanum (Phytopath. 1914, 4, 261—270). 
Während die meisten auf Pomaceen vorkommenden Rostpilze 
Ao^sA/Az-Fructification aufweisen, gibt es drei mit richtigen Aecidien: 
Aecidium Blasdaleanum Diet. et Holway, A. Sorbi Arth, und A. 
Pourthiaeae Syd. Verf. fand ein Aecidium auf Birnen und in der 
Nähe Gymnospor angium Blasdaleanum auf Heyderia decurrens; das 
gleiche Aecidium wurde auch auf Quitte, Sorbus sambucifolia und 5. 
spuria gefunden. Es gelang Verf. durch Infection mit Gymnospor angium 
Blasdaleanum die Aecidien auf Pirus communis , Cydonia vulgaris , 
Amelanchier alnifolia , Crataegus Douglasii und Malus rivularis hervor¬ 
zurufen; hierdurch ist bewiesen, daß Gymnospor angium Blasdaleanum 
auf den genannten Pflanzen seine Aecidien bildet. 
Riehm (Berlin-Dahlem). 
PETHYBRIDGE, G. H.,. Further observations on Phytophthora 
erythroseptica Pethyb., and on the disease produced by it 
in the Potato plant (Scient. Proc. Roy. Dublin Soc. 1914, 10 , 
179—198; 1 pl.). 
Pethybridge in this contribution gives further particulars of Phyto¬ 
phthora erythroseptica. The microchemical reactions of the walls of the 
liyphae, conidia, and sexual Organs show that these are largely, but not 
entirely, composed of cellulose. The walls of the oogonium and of the 
oospore eacli consist of two layers, the thin, outer portions being coloured 
with iodine reagents, and not dissolved by ammoniacal copper hydrate or 
concentrated sulphuric acid. The inner portion of each consists of cellulose, 
but that of the oospore differs from that of the oogonium in turning blue 
with iodine reagents instead of purplish-violet, and in being insoluble in 
ammoniacal copper hydrate. The thicker more hyaline apical portion of 
the conidium wall is not stained by iodine reagents, and is insolublej in 
concentrated sulphuric acid and in ammoniacal copper hydrate. It would 
appear that the conidial wall is composed largely of cellulose, but that 
its apical portion consists of some substance other than cellulose, whicli 
probably forms an extremely thin outer layer over the remaining portions 
of the wall. 
The conidia (zoosporangia) may germinate either by producing 
germ-tubes direct or by the formation of zoospores. The conditions whicli 
decide as to whether conidia shall produce germ-tubes of zoospores are 
not yet known. Observations on the germination whicli is essentially 
similar to that in other species of Phytophthora are described in detail. 
The zoospores are biciliate, one cilium being about twrice and the other 
about three times as long as the zoospore. 
The oospores have been caused to germinate after a suitable period 
of rest. Previous to the production of a germ-tube by the oospore, whicli 
19 * 
