22 
POPULAR SCIENCE REVIEW. 
the yellow dust the spores,* or ultimate representatives of 
seed, and the epiphytal plants we have here found we will 
accept as the type of the group or order to which we wish to 
direct attention (plate II. figs. 1 — 3). 
Amongst the six families into which fungi are divided is one 
in which the spores are the principal feature, as is the auran- 
tiaceous dust in the parasite of the goatsbeard. This family 
is named Goniomycetes , from two Greek words meaning “ dust- 
fungi.” This group or family includes several smaller groups 
termed orders, which are analogous to the natural orders of 
flowering plants. Without staying to enumerate the charac- 
teristics of these orders, we select one in which the spores are 
enclosed in a distinct peridium, as in our typical plant they are 
contained within the cups. This order is the JEcidiacei, so 
called after JEcidium, the largest and most important of the 
genera included within this order. 
The JEcidiacei are always developed on living plants, some- 
times on the flowers, fruit, petioles, or stems, but most 
commonly on the leaves : occasionally on the upper surface, 
but generally on the inferior. The different species are dis- 
tributed over a wide area ; many are found in Europe and 
North America, some occur in Asia, Africa, and Australia. 
When the cryptogamic plants of the world shall have been as 
widely examined and as well understood as the phanerogamic 
plants have been, we shall be in a better position to determine 
the geographical distribution of the different orders of fungi. 
In the present incomplete state of our knowledge, all such 
efforts will be unsatisfactory. 
But to return to the goatsbeard, and its cluster cups. The 
little fungus is called JEcidium tragopogonis, the first being 
the name of the genus, and the last that of the species. Let 
us warn the young student against falling into the error of 
supposing because in this, and many other instances, the 
specific name of the fungus is derived from the plant, or one 
of the plants, upon which it is found, that therefore the species 
differs with that of the plant, and that, as a rule, he may 
anticipate meeting with a distinct species of fungus on every 
distinct species of plant, or that the parasite which he encoun- 
ters on the living leaves of any one plant is necessarily specifi- 
cally distinct from those found on all other plants. One 
species of JEcidium , for instance* may hitherto have been 
found only on one species of plant, whereas another JEcidium 
may have been found on five or six different species of plants. 
The mycologist will look to the specific differences in the 
* Protospores, they should be called, because in fact they germinate, and 
on the threads thus produced the true spores, or fruit, arc borne; 
