164 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



consult special works. Of course the spores are a 

 source of danger, but need be by no means so much so 

 where knowledge is intelligently applied in removing 

 young fructifications. 



I will now pass on to a few remarks on a class of 

 disease-producing timber fungi which present certain 

 peculiarities in their biology. The two fungi which 

 have been described are true parasites, attacking the 

 roots of living trees, and causing disease in the timber 

 by travelling up the cambium, &c., into the stem : the 

 fungi I am about to refer to are termed wound- 

 parasites, because they attack the timber and trees at 

 the surfaces of wounds, such as cut branches, toi 

 bark, frost-cracks, &c., and spread from thence into 

 the sound timber. When we are reminded how many 

 sources of danger are here open in the shape of 

 wounds, there is no room for wonder that such fungi 

 as these are so widely spread. Squirrels, rats, cattle, 

 &c., nibble or rub off bark ; snow and dew break 

 branches ; insects bore into stems ; wind, hail, &c., 

 injure young parts of trees ; and in fact small wounds 

 are formed in such quantities that if the fructifications 

 of such fungi as those referred to are permitted to 

 ripen indiscriminately, the wonder is not that access 

 to the timber is gained, but rather that a tree of any 

 considerable age escapes at all. 



