PECULIARITIES OF PLANTS. 
Until the great question of the origin of “ mould ” or mouldiness upon plants 
be settled, it will be futile to make any positive assertion upon the subject. 
Microscopic research has appeared to prove that every species is a vegetable organic 
body, of a strictly Cryptogamic structure, but so entirely distinct from that of plants, 
commonly so called, as almost to sanction the opinion — once generally entertained, 
and still formed by persons who neither read nor investigate — that mould is the 
result of rottenness and decay. 
There is one general fact which may be safely adduced, before we quit the 
subject, it is this : — whatever may be the origin of mould (assuming that it is 
essentially & fungus), each and every individual species or variety has its peculiar 
season of appearance and growth ; and whether it fix itself upon any living plant, 
or upon any effete matter as its appropriate medium of support, being deposited 
thereon by vivifying sporules floating in the air, or emerge from the body itself as 
an educt , in consequence of some change in the components of that bod}-, certain 
it is that its appearance is arbitrary, and governed by some determinate, though 
unknown law. 
A new publication commenced September 5th last, its title — “ The Pharma- 
ceutical Times.” In its third weekly number, pp. 45-7, there is an article written 
by Dr. Ayres of London, expressly upon the Disease of the Potato. As a whole it 
is excellent ; but there is one passage so relevant to the parasitic diseases of plants, 
that we venture to offer a considerable portion of it to the consideration of those 
cultivators who are curious in Cryptogamic Botany. 
In viewing the question whether parasitic fungi are to be considered as a cause 
cr a concomitant of disease, Dr. Ayres considers it essential to inquire into the 
habits and growth of the fungi ; and he says — “For our present purpose we may 
livide these forms of vegetables into two classes ; those which infest living plants, 
and those which inhabit dead animal or vegetable matter. It is well known that 
die greater part of the fungi live or grow on the earth, particularly where it has 
been well manured by the decay of large quantities of organic matter, or stumps of 
trees, or stems or other parts of dead plants ; but there are tribes, which like the 
cntozoa ” ( evros within, and Cam living beings) “ among animals, infest the living 
plant, or some particular organ of the plant. The smut of corn and other plants, 
nay be mentioned as an example. Their epiphytic fungi do not necessarily destroy 
die plant unless in excessive abundance, although in all cases they render it less 
rigorous ; or merely some part is destroyed as in the smut of wheat ( TJredo segetum) 
vhere the ovary is filled with the sporules of the uredo instead of the grain. There 
ire other fungi which make their appearance on parts of the leaves which have 
Jecome unhealthy, have lost their ordinary green, and turned brown or yellow, showing 
VOL. XIII. NO. CLIV. 
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