INFECTION-POWERS OF ACOSPORES IN ERYSIPHACER. 159 
eee this plant to have been destroyed by drainage and cultivation, 
though formerly abundant in several localities. Mr. Fryer found 
it at Wimblington- otha Firelots, 1884 (Journ. Bot. 1899, 245). 
INFECTION-POWEBRS or ASCOSPORES 1 ERYSIPHACEA. 
By Ernest 8. Satmon, F.L.S. 
Dvunine the past months I haye carried on a series of al 
tion- savianiianiey: using the ascospores of Erysiphe Graminis DC. 0 
ordeum vulgare. The experiments seem to show conclusively that 
the infection- ges of the asco ospores, on whic 
hitherto been known, are restricted in a definite manner. It is im- 
srosain to give “tebe the full details of the experiments, of the be- 
haviour of the ascospores in various media, the penetration of the 
germ- ‘etibe and the formation of the first haustorium, &c., and the 
object of this preliminary note will be to summarize the chief points 
of interest. In order to estimate the peculiar importance which the 
with these fungi. DURE the last year experiments carried on by 
‘‘ biologic forms ”’ of a species are morphologically identical, while 
differing physiologically or biologically, as is shown by the fact that 
— behave differently towards the same host-plant. Although the 
xistence of such forms was suspected _by some of oat older meee 
igi (cfr. De Bary’s (1) p. 884) * interesting r mo ge 
s a ct), definite experiniental proof has ‘thy recen soe 
giv 
beth a critical concaest A of these will be found in my oo 
(4), who pee that the forms - tiene Cie sha acaiielen on Lie te- 
misia vulgaris, Hieracium murorum, and Senecio vulgaris; the forms 
of E. Polygont on Heracleum Sphondylium and Trifolium incarnatum ; 
and the form of F. Galeopsidis on Galeopsis Tetrahit constituted in 
each case a “biologic form,” the conidia being unable to infect 
h 
appear pape 
sches Centralblatt Jeter in prcide re The fu ze agus oes bo es 
ments was the conidial ( Oi stage of Erysiphe Gra 
E. Polygoni. Evidence was obtained of the existence of ‘ ‘ biologie 
ne abe oaionsms: ) a ance 
fer to the bibliography given at p. 165. 
* TM, } ¥ 
uv oe € Oo 
