MOULDS. 193 
but it is not our province here to enter upon the discussion of 
such a subject. 
The association of one-ceiled orange-coloured spores with 
the brown two or more celled spores passed in review is 
another feature worthy of passing notice, which opens another 
field for discussion. It is generally admitted that these two 
forms are the production of the self-same mycelium or vegeta- 
tive system, but it is not so generally admitted that they are 
but two forms or phases of the fruit of the same plant. It is 
not at all uncommon in the history of mycology to find two 
forms which were for a long time considered to be distinct 
plants producing different forms of fruit, and which bore 
different names, and were located in different genera, at length 
proved to be only the self-same plant in different conditions, 
and ending in one name being expunged from the list. Such 
a fate probably awaits, at no distant date, the orange spores 
which precede or accompany the species in the present genera. 
Already Tulasne and some others accord them no place in their 
system. 
It may be added, for the benefit of any who wish to pursue 
the study of this interesting branch of Cryptogamic Botany, 
that the leaves of the plants containing the parasitic Fungi now 
noticed may be collected and preserved by drying between 
folds of blotting-paper, or the leaves of a book, and will 
retain their character, with the exception of colour in the 
orange forms, so as to be eligible for examination at any 
period of the year for twenty years to come. Each species, 
when dry, may be transferred to an old envelope, and labelled 
outside with the name, date of collection, and locality; and one 
hundred such envelopes will constitute a miniature herbarium 
in a very small compass. 
MOULDS. 
T WENTY years since and some of these little pests were 
altogether unknown, whilst others were only recognized 
and partly understood by a few scientific men. During the 
period to which we have alluded more than half the present 
species contained in the genus Peronospora had never been 
observed, and amongst these the most devastating of its tribe, 
the associate and undoubted cause of the potato disease. 
Parasitic fungi are far more numerous, both in individuals 
and species, than most persons are aware, and cultivated 
