40 Finger and Toe, and Wart Disease [cH. 
The plant has to give up some of its food to the 
development of the plasmodium, at the same time it 
continues to grow and manufacture fresh food material. 
As the plasmodium grows bigger it requires considerably 
more food material and consequently the plant growth 
is lessened until a time is reached when the plant 
ceases to grow, or grows only very slowly, the whole 
of the food manufactured by the leaves or brought 
up by the roots going to the support of the plas- 
modium. 
The formation of giant cells causes the roots to 
become swollen, and when a portion of the fungus 
proceeds in a certain direction nodules are formed, 
until eventually a state of affairs is reached as shown 
in Fig. 12. 
After a time the plasmodium becomes divided up 
into a large number of small portions, each of which 
becomes spherical and surrounds itself with a definite 
cell wall. These spherical bodies are the spores. 
When the host rots these spores are set free in the soil 
ready to start on their destructive career, when the 
favourable conditions of spring bring about their 
germination. It is supposed that they can retain their 
vitality for several years, which characteristic is 
extremely favourable to the fungus in the ordinary 
rotation of crops. This longevity of the spores, together 
with the presence of certain cruciferous weeds which can 
act as hosts of the fungus, enables it to continue its 
existence when cruciferous plants are grown every 
four or five years. 
There are other diseases known as “club,” which 
cause similar distortions to plants. One of these is 
caused by a weevil which may be found inside the 
