186 FUNGI. 
graminis) which succeeded it. The simple spored rust first 
makes its appearance, and later the bilocular “ mildew.” It is 
by no means uncommon io find the two forms in the same pus- 
tule. Some haye held, without good reason, that the simple 
cells became afterwards divided and converted into Puccinza, 
bat this is not the case; the uredo-spores are always simple, and 
remain so except in Uredo linearis, where every intermediate 
stage has been observed. Both are also perfect in their kind, 
and capable of germination. 
What the precise relations between the two forms may be has 
as yet never been revealed to observers, but that the two forms 
belong to one species is not now doubted. Very many species 
of Puccinta have already been found associated with a corre- 
sponding Zrichobasis, and of Phragmidium with a relative Lecy- 
thea, but it may be open to grave doubt whether some of the 
very many species associated by authors are not so classed upon 
suspicion rather than observation. We are ready to admit that 
the evidence is strong in favour of the dimorphism of a large 
number of species—it may be in all, but this awaits proof, or 
substantial presumption on good grounds. Up to the present we 
know that there are species of Trichobasis which have never 
been traced to association with a Puccinia, and doubtless there 
will be species of Puccinia for which no corresponding Uredo 
or Trichobasis can be found. 
Tulasne remarks, in reference to Puccinia soncli, in one of his 
memoirs, that this curious species exhibits, in effect, that a Puc- 
cinia may unite three sorts of reproductive bodies, which, taking 
part, constitute for the mycologists of the day three entirely dif- 
ferent plants—a Trichobasis, a Uromyces, and a Puccinia. The 
Uredines are not Icss rich, he adds, in reproductive bodies of 
divers sorts than the Fyrenomycetes and the Discomycetes; and 
we should not be surprised at this, since it seems to be a law, 
almost constant in the general harmony of nature, that the 
smaller the organized beings are, the more their races are 
prolific. 
In Puccinia variabilis, Grev., it is common to find a unicellular 
form, species of Trickobasis, in the same pustules. A like circum- 
