Los 
ROYAL GARDENS, KEW. 
BULLETIN 
MISCELLANEOUS |. INFORMATION. 
Nos. 153-154.] SEPTEMBER and OCTOBER. (1899, 
DCLVI—A REVISION OF THE GENUS TILLETIA. 
(With Plate.) 
GEO. MASSEE. 
All species included in the genus, as at present defined, are 
ne en obligate parasites, and out of a total of twenty-six 
species, all are parasitic on plants belonging to the Graminese, with 
the siii on = re pam Rostr., and T. Sphagni, Nawas- 
chin. The for of thes s parasitic on Carex festiva, Dewey, 
and the latter di the Notice d of Sphagnum squarrosum, Pers. 
The infested pg croton are somewhat dwarfed, and form ed what 
ere known rosporangia by bryologists, while the Ares 
spores they retirees were called microspore 
In the Uredinez what vat be termed biological species have 
been proved to exist; that is to say, of a species one or more forms 
not mortipfogiédibe u may exist, that are distinguishable 
only by the fact that they are confined to one particular host-plant. 
Professor Eriksson, our best authority on grain-rusts, has the 
following remarks* on this phase of the subject :—“ Between 
certain of these forms which constitute a species, for instance, "as 
three forms of black rust—Puccinia graminis, Pers,—we hav 
not succeeded in discovering, even with the aid of a iaisraicapis 
c ch as 
However there is a difference 3 betw ween them with regard to thei 
nner hog in that «d of no little raona interak The difference 
sped S in that every form is almost exclusively confined to its 
part Fioulat cereal, ud that consequently it is able to infect no 
cereal but that one." 
* Eriksson in Bot, Gaz. xxv. (1898), p. 29, 
3790—1375—10/99 Wt92 D&S 29 
