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POPULAR SCIENCE REVIEW. 
species will be found accompanied by the orange spores of 
species of Lecyt/iea , which some mycologists consider to be 
distinct Fungi, and others to be merely forms or conditions of 
Aregma These spores are represented in figs. 3, 6, 9, and 
12. From the magnified figures of the spores of the different 
species of Aregma (figs. 4, 7, 10, and 13), it will be apparent 
that they have all certain features in common, i.e., cylindrical 
spores containing from three to seven cells. This may be 
called the generic character, common to all the species of the 
genus Aregma. Again, each species will be observed to 
possess its own distinct features, which may be termed its 
specific character. In one, the apex of the spores will be 
obtuse, in another acutely pointed, in another bluntly pointed, 
&c. In one species the number of cells will usually be four, 
in another five or six, in another seven or eight. The stem in 
one species will be slender and equal, in another thickened or 
bulbous. So that in all there will be some permanent 
peculiarity for each not shared by the others. 
One other form of brand, presenting, it is believed by some, 
generic differences from all that we have as yet noticed, remains 
to be briefly alluded to. This form appears to be very uncom- 
mon in this country, but, when found, is parasitic on the leaves 
of the great burnet ( Sanguisorba officinalis ), a plant of local 
distribution. The parasite appears to the naked eye in small 
tufts or pustules resembling those of an Aregma } but, when 
microscopically examined, the cells of the spores are found to 
be numerous, indeed, considerably more than in the most com- 
plex Aregma (fig. 1). This, however, seems to be the only 
distinction, for the cells are free in the interior of the investing 
membrane, and in all points of structure, in so far as it has 
been examined, identical with Aregma. Whether it is logical 
to consider a four-celled spore an Aregma , and a seven-celled 
spore an Aregma 3 and exclude a ten or twelve-celled spore 
from the same genus on account of the number of its cells, 
does not appear to us clearly answerable in the affirmative. 
During the course of this paper we have passed rapidly 
through four genera of parisitic Fungi so nearly allied, that one 
is almost led to doubt the validity of the generic distinctions. 
These may be presented briefly thus, — 
Puccinia spores two-celled. 
Triphragmium „ three-celled. 
Aregma „ four to seven-celled. 
Xenodochus „ many-celled. 
It has been seen that the habit, mode of growth, germination, 
and structure, except in the number of cells, scarcely differs ; 
