34 
POPULAR SCIENCE REVIEW. 
and also the goatsbeard, in which the cluster- cups^are arranged 
in no appreciable order, the spermogones are scattered 
amongst them, and even in some instances appear on different 
leaves. The spermogones are common on the wood spurge 
in spring, scattered over both surfaces of the leaves before 
the cluster-cups make their appearance, and gradually these 
latter are developed amongst them, commencing from the apex 
of the leaves and proceeding in the order of their development 
towards the base. In this instance the spermogones are bright 
yellow, as are afterwards the cups and spores of the JEcidium. 
In most instances the appearance of the spermogones precedes 
that of the sporiferous organs, but the latter follow sufficiently 
speedy for perfect development before the decadence of the 
spermogones takes place. 
After the expulsion of the spermatia and the fluid which 
accompanies them, the whole mass dries up ; and where many 
spermogones have been clustered together in the same spot a 
brown homogeneous crust is formed upon the epidermis ; where 
they are produced singly, a brownish incrustation is visible 
about the mouth of each spermogone. 
Re-agents applied to the spermogones whilst in full vitality 
indicate the presence of a considerable amount of a protein 
substance, which, with sugar and sulphuric acid, produces a 
deep purple red colour. 
From what we have already stated of the method of occur- 
rence of these organs, the following is the only order, 
apparently, preserved in their development, although no definite 
rules can at present be affirmed. The spore-spots or cluster- 
cups are generally found upon the under surfaces of the leaves 
on which they are produced, and the spermogones are most 
numerous on the upper. When both the cluster- cups and the 
spermogones appear in the same group on the same surface, 
the spermogones commonly occupy the centre, and the cups 
are arranged in a circular manner about them. In other, and 
fewer instances, both organs stand together indiscriminately 
upon the same surface. 
The spermogones are also developed centrifugally, at least 
so far as at present observed, for when they are produced in a 
cluster the central one first opens and discharges its contents, 
and thus the development proceeds outwards from the centre 
to the circumference. When the spermogones are scattered, 
as in those of j Euphorbia, they are first observed at the apex 
of the leaf, whence they are developed in succession towards 
the base. The latter should be sought for on the young plants 
of the wood-spurge in March or April, at which time we have 
found them abundant at Rarenth wood, near Dartford. 
It must not be concluded, from the fact that we have not 
