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“storage of the food materials manufactured in the ‘leaves. 
The reserve supplies are thus tapped by the fungus, with 
the result that the quantity of sugar stored by the grow- 
ing root rapidly diminishes. In such instances many of 
the cells of the root are enormously enlarged and differs 
as regards their contents from those of a healthy root. ° 
The healthy cells are lined by the colourless, jelly-hke, 
living protoplasm with its nucleus and contain cell-sap rich 
in sugar. Diseased cells differ from these in several re- 
spects. They are generally much larger; protoplasm is 
present as before, but it looks frothy and in it can be seen 
granular masses of other slimy substance which is the 
protoplasm of the fungus slowly absorbing that of its 
victim. It is a remarkable fact that the early effect of the 
parasite upon the cell is to stimulate it to enlarge and 
even to divide, and thus obtain more food material from 
the adjoining cells, and this is ultimately used by the 
unbidden guest. Gradually the protoplasm of the fungus 
increases in size until the whole of the protoplasm of the 
cell disappears. Then the fungus undergoes certain 
changes and soon the cell is seen to be filled with a large 
number of tiny round bodies. These are the spores of the 
fungus, and as they only measure one fifteen thousandth 
of an inch in diameter they can only be seen when very 
highly magnified. A single diseased cell will contain at 
least 100,000 of these spores, and since the diseased part of 
a turnip, for example, contains many thousands of such 
cells it is easy to see that in one such root millions of the 
spores of the fungus are produced. 
If a very small piece of a diseased root is broken up in 
water myriads of the spores are liberated from the cells. 
After a few hours very remarkable changes can be observed 
to take place in these. Each tiny spore swells somewhat 
and then bursts producing a small hole in one side of the 
colourless membrane. Gradually the living protoplasm 
within squeezes its way through the aperture thus formed. 
As soon as it is free it begins to wriggle and move about 
as a minute speck of living protoplasm. The protoplasm 
at one end is drawn out into a fine hair, and the 
lashing of the water by this hair causes the movement of 
the minute organism. After a time the, movements of 
these specks of protoplasm become more sluggish and soon 
they only creep about by slow movements, first pushing 
one part of the protoplasm forward and dragging the 
