330 
POPULAR SCIENCE REVIEW. 
similar to those of the last species, save that the cells are 
smaller, and a larger number are collected together. So far 
as I have yet examined the spores of this and the preceding 
species, they appear to consist of separate and distinct vesicles 
(probably spores), contained within a hyaline sac or outer 
membrane, and not to be a single spore divided into cells by 
numerous septa. 
A species of equal interest ( Polycystis Colchici, Tul.) is 
found^on the autumnal crocus, or meadow-saffron ( Golchicum 
autumnale). The spores approach nearer to those of the last 
than of the prior species. 
A fourth species occurs on the leaves of rye, forming elon- 
gated parallel blackish lines (. Polycystis jparallela , B. & Br.). 
It has also been found on the leaves of some grasses, but 
does not appear to be very common. 
Small as this genus is, — for I have named all the British 
representatives, its compound spores are beautiful objects for 
the microscope. It may not be altogether out of place to 
state, that I have found glycerine a very good medium in 
which to mount them for preservation, although I have usually 
employed balsam, for an idle reason which microscopists will 
appreciate. Deane’s gelatine is more difficult of manipulation, 
or I may have been in fault, as well as my friends who have 
endeavoured to use it. 
I well remember, in my younger days, before I had devoted 
myself to Fungi, and when I knew or recognized but little 
more than two or three kinds, how one or two little things 
puzzled me, as perhaps they may have puzzled others. I 
never could comprehend the mystery of smutted corn, nor 
understand what could cause the white rust. In a retired 
agricultural district, with no one to enlighten me, I continued 
to study such of the flowering plants as the locality yielded, 
and amused myself by making sketches of diseased leaves, 
and other like phenomena, which interested and puzzled me, 
and in fact, sometimes haunted me in dreams. One of these 
mysteries was the white, elevated, concentric spots on the 
leaves of cauliflowers and cabbages. In some years this 
singular appearance is very common. The leaves become 
depressed on the opposite surface to that on which white, 
elevated, irregular spots are seated, having a circular outline, 
but disposed in the manner represented in the plate (Plate XIII. 
fig. 15). These spots look like white paint or whitewash, not 
thrown on carelessly, but arranged and traced by an artist’s 
hand. Sometimes one and sometimes twenty of these groups 
occur on the same leaf, and I now know that these spots are 
by no means confined to plants of the cabbage kind, but 
appear on numerous other plants belonging to very different 
