172 PLANT LIFE 
region, and also in the sapwood of the tree, . 
but the special point of interest about this 
fungus lies in the circumstance that black 
cord-like mycelial strands are produced in the 
tree by the approximation of hyphe, which 
then become woven into thin strands. These 
grow as organised structures, and some of 
them force their way out of the tree below 
the surface of the soil, there continuing to 
elongate till they reach the roots of other 
pines. They then enter these, and so the 
pest may easily assume the character of an 
epidemic, extending from one pine to another 
as from a centre, and killing the trees in its 
advance. 
CHAPTER XV 
FUNGAL PARASITES 
TuE history of our cultivated plants, both 
in Europe and, to a far greater extent, 
in the tropics, bears abundant testimony to 
the magnitude of the evils caused by fungal 
enemies. The conditions under which crops 
are generally grown happen, unfortunately, to 
