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POPULAR SCIENCE REVIEW. 
seed with, the flat surface downwards, sprinkling the under 
surface of blackberry leaves, with larger reddish, purplish, or 
reddish-brown spots on the upper surface to indicate the pre- 
sence of the fungus beneath. Just at the time when black- 
berries are ripe, these spots are in perfection on the leaves, 
and their eyes must have been 'sadly at fault who could ever 
have gathered their own blackberries without seeing the dis- 
coloured leaves. The coloured spots on the face of the leaf 
are due to the diseased state of the tissues caused by the 
parasite on the opposite surface. As much of the leaf as 
contains two or three of the black pustules should be removed 
carefully with a knife or sharp scissors, and submitted to 
microscopical examination ; each will be seen to consist of a 
dense tuft of blackish, elongated, stalked bodies, clustered as 
in fig. 16, but much more numerously and closely packed 
together. These are the spores of the blackberry brand (Aregma 
bulbosum, Fr.). A few of these spores should be removed 
on the point of a sharp penknife, placed on a glass slide with 
a drop of distilled water or alcohol, covered with thin glass, 
and then viewed with a quarter-inch objective. 4 Each spore 
has a stalk longer than itself, thickened below, and containing a 
yellow granular core. The spore itself is much longer than in 
any of the Puccinice , of a dark brown colour, and apparently 
divided by several transverse partitions into three, or four, or 
more cells, the whole surface being covered with minute warts 
or prominences (fig. 13). In 1857, Mr. F. Currey investigated 
the structure of these spores, and the results of his experiments 
were detailed in the t( Quarterly Journal of Microscopical 
Science.” One conclusion arrived at was, that “ the idea of the 
fruit consisting of sporidia united together and forming a chain, 
is certainly not in accordance with the true structure. The 
sporidia are not united to one another in any way, but, although 
closely packed for want of space, they are in fact free in the 
interior of what may be called a sporangium or ascus.” To 
arrive at this conclusion, careful examination was necessary, 
and new modes of manipulation essential. The details of one 
method employed were to the following effect : — A sufficient 
number of spores were removed on the point of a lancet, and 
placed on a slide in a drop of alcohol. Before the spirit was 
quite evaporated, two or three drops of strong nitric acid were 
added, and the whole covered with thin glass. The slide was 
then warmed over a spirit-lamp, the acid not being allowed to 
boil, but only gradually heated to boiling point. By this 
means the fruit was found to consist of an outer membrane, 
nearly transparent, and studded with tubercles; that this 
membrane enclosed a number of cells which constituted the 
apparent joints, and which were naturally flattened at either 
