THE 
HEW PHVTOItOGIST 
Vol. 3, No. 5. 
May 30TH, 1904. 
ON SPECIALIZATION OF PARASITISM IN 
THE ERYSIPHACEAE, II., 
By Ernest S. Salmon. 
N a previous paper * 1 on the present subject I have recorded the 
results of a series of comparative inoculation-experiments 
which showed that a far-reaching specialization of parasitism has 
taken place in certain species of the Erysiphaceae. 
The present paper gives the results of further inoculation- 
experiments, carried out during the past summer, in which conidia 
of the following species were used :— Erysiphe Graminis DC., on 
A vena sterilis, Agropyron repens, Poa pratensis, and Dactylis glo- 
merata ; Sphacrotlicca Humuli (DC.) Burr, on Potentilla reptans ; 
S. Hamuli var. fuliginea (Schlecht.) Salm. on Taraxacum officinale 
and Plantago lanceolata ; E. Cichoracearum DC. on Plantago major ; 
and E. Galeopsidis DC. on Ballota nigra . 2 
The results obtained seem to show that in every case the form 
of the fungus used has become specialized into a “ biologic form .” 3 
Two points of special interest may be noticed here, viz. proof 
of specialization of parasitism in Sphaerotheca, a genus in which 
comparative infection-experiments had not hitherto been carried 
out; and the formation of perithecia on inoculated leaves of 
Taraxacum officinale, Plantago major, and P. media. 
In all the above cases conidia of the fungus were used. It may 
be noted here, however, that so far as experiments have been made, 
1 Beikefte z. Botau. Ceutralbl. XIV. 261-315 (1903). 
3 The results of a series of experiments carried out at the same 
time, in which E. Graminis on various species of Bromus 
was used, are not included here. These will appear in a 
paper in the next number of the “ Annates Mycologici.” 
3 A general account of the phenomena met with in the speciali¬ 
zation of parasitism in the Erysiphaceae, and a definition of 
“ biologic forms,” have been given ty' the writer in a recent 
number of this journal (p. 55.) 
