8 THE NORTHERN MICROSCOPIST. 

mn INTRODUCTION. TO HE Sry 
OF FUNGI. 
By ey ancy sag)) th, “Waiznes McA, 
Concluded from page 281. 
ae resting spore even under the level of the ground knows, in 
common with all vegetable life, the right time to grow. In June 
and July it is ready to mature, and if it gets sufficient moisture it 
is full of life, and if it touch a tuber, at once its mycelium penetrates 
it, extends up the haulms and goes to the leaves, proving its pre- 
sence by the growth of itself there, and by the absorption and 
destruction of the vital properties of the leaf, thus turning it to the 
brown color we see on it. Possibly some of you may like to know 
some of the wonders the microscope reveals at this brown spot. 
To make it clear to you, it will be well to remember that the leaves 
of all plants which do not live in water are not what they appear 
to be, namely, green things with a thin film or coating on each 
side to keep it together. The films, or more properly speaking 
cuticles, are beautifully arranged so as to admit and consume 
moisture and air. These are called stomata, stomates, breathing 
pores or mouths. It is estimated that in every separate leaf of the 
potatoe plant there are 100,000 of these mouths. The fungus of 
the potatoe when on the leaf always grows in these mouths, and 
not elsewhere on the leaf, as some of its allies do. The growth 
then is made, and we get the leaf full of mycelium or thread-like 
roots. But there are not only growths inside; if you notice the 
leaf even with the naked eye, but especially under the microscope, 
you will observe a grey tint or bloom upon it. This tint consists 
of a tree-like growth, upon-which are borne two kinds of spores or 
seeds, both of which are capable of growth during the moist suni- 
mer weather when they find the right place to develope, but neither 
of which will exist in winter ; they must die. One kind of spore 
we call the conidia, or dust spore. It grows at the end of the 
branch, and when ripe will drop or be wafted by the wind to 
another leaf or the stem of the potatoe where it will grow again ; 
it will even start into existence on many a damp place, but will 
quickly die unless it can find a mouth of the potatoe leaf or stem, 
or some very closely related leaf of the family to which it belongs, 
on which it grows. When it has found its habitat, the moisture in 
due time causes the corrosive matter of which the spore is com- 
posed to expand, and with it vegetation gets to work, and increases 
the potatoe disease. 
But we were saying there is another kind of spore, on the 
