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POPULAU SCIENCE REVIEW. 
them, and suggests that the cystidia are only organs returned 
to vegetative functions by a sort of hypertrophy of the basidia.” 
This view is supported by the fact that in the section Pluteus 
the cystidia are surmounted by short horns resembling sterig- 
mata. Hoffmann has also indicated the passage of cystidia into 
basidia Zeit 1856, pp. 139). All the evidence seems to 
be in favour of regarding the cystidia as barren conditions of 
hasidia. 
There are in the hymenium-a third kind of elongated cells, 
called by Corda* “basilary cells,” and by Hoffmann “sterile 
cells,” which are either equal in size or smaller than the basidia, 
with which also their structure agrees, excepting in the deve- 
lopment of sterigmata (fig. 5 a). These are the “proper cells 
of the hymenium ” of Leveille, and are simply the terminal cells 
of the gill structure — cells which, under vigorous conditions, 
might be developed into basidia, but which are commonly 
arrested in their development. As suggested by Seynes the 
hymenium seems to be reduced to great simplicity : “ one sole 
and selfsame organ is the basis of it ; according as it experiences 
an arrest of development, as it grows and fructifies, or as it 
becomes hypertrophied, it gives us a ^araphyse, a basidium, 
or a cystidium, in other terms, atrophied basidium, normal 
l)asidium, hypertrophied basidium : these are the three elements 
which form the hymenium.” 
The presence of male organs, or antheridia, or anything 
analogous thereto in the mushroom, and in fungi of the mush- 
room type, has yet to be demonstrated. Hitherto all efforts to 
discover them appear to have failed. The only reproductive 
organs, therefore, with which we have to deal are the spores. 
Tliese are sometimes called basidiospores, because they are borne 
at the summit of the cells termed basidia. It has been noticed 
already that they are tetrasporous, that is, they are produced in 
groups of four to each basidium. The spores are at first colour- 
less, in some species they remain so, in others they pass to some 
shade of brown. The variety of tint, form, and size of the 
spores of agarics is so great that it would be difficult to enume- 
rate. Anyone desirous of studying them can do so with little 
trouble by placing the pileus of fresh specimens, gills down- 
wards, on slips of glass, and protecting the spores so obtained 
l)y tliin covers, in the usual way. The spore envelope is con- 
sidered to be composed of two membranes — the external, or 
more tenacious, l)eing the exosporium, and the internal, more 
delicate, the endosponum. It is always the external membrane 
which is coloured. The spore contents are the same as those of 
• “leones Fiingonim hucusqne cognitonim.” Tomus iii., p. 41. Pragee, 
1839. 
