XXX 
INTRODUCTION. 
conceal within themselves during the winter a large number of 
these “ resting spores.” As the old stems rot and decay the 
resting spores are set free in the spring, and then a period of 
activity commences. The contents of these globose bodies 
become differentiated into a largo number of zoospores, which 
ultimately escape, by a rupture of the thick envelope, armed 
with vibratile cilia, and in all l’espects like the zoospores 
which are developed from the conidia. These active zoospores 
swarm over the damp soil, and are carried by the spring rains 
into proximity with the young seedling leaves of the new crop 
of host plants, then the cilia are absorbed, germination com- 
mences, the delicate threads of mycelium enter the nearest 
stomata, and infection results. In this way, in addition to the 
spread of the infection from conidia in summer and autumn, 
provision is made for an attack upon seedlings in the spring. 
It will be inferred that, in order to check the spread of these 
diseases, the conidia must be destroyed in the autumn, to 
prevent their extension to healthy plants, and the destruction 
of all rotting debris must be carried out during the winter, so 
as to extirpate all the concealed resting spores, and thus 
prevent the infection of seedlings in the spring. Thus it will 
be seen that a knowledge of the life history of these parasites 
will suggest the best methods to be employed in their destruc- 
tion. 
With these suggestions we must quit a subject which would 
require considerable space to illustrate fully, or we might 
allude to such corn diseases as “ rust ” and “ mildew,” in order 
to demonstrate still further that all hope of alleviating the 
mischief they cause must be based upon knowledge of the con- 
ditions favourable or unfavourable to the reproduction and dis- 
semination of the specific diseases. 
It cannot be considered out of place to urge the importance 
which attaches to fungi, as well as to other branches of the 
Cryptogamia, that for the purpose of determining the species, 
and even the genera, the specimens collected should be in a 
perfect and fructifying condition. A very casual glance at the 
following pages will be sufficient to carry the conviction that 
everything depends upon the spore, or its analogue. The true 
relations of an Agaric can only be sought for after the deter- 
mination of the colour of the spores. All the minute species 
in which the fructification is enclosed in a perithecium, having 
the habit of a Sphceria, must, in the first instance, exhibit fruit 
before it can be affirmed whether, by virtue of the presence of 
asci, it should have its place in the Ascomycetes, or, on account 
of their absence, among the Sphxropsidew.. Moulds, again, 
which are devoid of conidia, are no better than a condition of 
mycelium, and their relations cannot even be guessed at. 
Spotted leaves are collected by novices, almost in myriads, 
under the impression that whenever a living leaf has become 
spotted, such spotting is produced by a fungus. The assump- 
