NOTES ON THE ERYSIPHACEAE 17 
must have been already naturally infected by the Ozdiwm on the 
raspberries before being experimented upon. 
With regard to Magnus’ experiment (1), I have already 
(monograph, p. 18) pointed out the special difficulties which arise 
if we consider that the Ozdium which appeared on the Taraxacum 
really resulted from the sowing of the conidia of S. humuli from 
the hop. 
Experiment (2) would seem, if scientific precautions were taken 
to prevent the access of other conidia to the tobacco leaf under 
observation, to prove satisfactorily that Erysiphe cichoracearum can 
pass from the leaves of a host-plant belonging to the Compositae 
to one belonging to the Solanaceae. 
The acceptance of the conclusions drawn by .Neger from his 
experiment (3) involves us in the same difficulties as in the case 
of Magnus’ experiment. If the conidia of £. polygoni were really 
the ones that produced the Ozdium on the Galium (the fact that 
the Ga/ium plant was kept under a bell-jar does not, unless special 
precautions were taken, preclude the possibility of infection by 
other conidia having taken place) it seems strange that we do not 
find in nature FE. polygoni occurring on Galium. It is true that 
many authors have recorded “4. communis’ or “&. Martit’””»— 
synonyms of £, polygoni—on species of Galium, chiefly G. Aparine, 
but this has always been due, I believe, to a wrong identification 
of the fungus having been made, as in all cases investigated the 
_ fungus has proved to be £. cichoracearum (see monograph, p. 20). 
It is to be noted, too, that Neger expressly states that the Ozdium 
which appeared on the Ga/ium showed morphological differences 
from that on the Ranunculus—a fact certainly favorable to the idea 
that infection from some other source had taken place. 
With regard to case (4) I have, through the kindness of Profes- 
sor P. Magnus, seen Allescher’s specimen of “ J. Ehrenbergu”’ on 
Syringa vulgaris. The fungus, which is certainly growing on this 
host, as the presence of mycelium and young perithecia show, 
presents the characters of the var. /onicerae (= M. Ehrenbergit) 
rather than those of the JZ. a/ni type (which grows commonly on 
Syringa vulgaris in the United States). It seems, therefore, that 
we can, as Magnus (Bericht. deutsch. bot. Gesellsch. 16: 68. 
1898) has done, accept the case as affording proof that the var. 
