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 hyphse, 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 



THE 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 



