162 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



of the pines, &c.) into the resin passages. The hyphae 

 of the ultimate twigs enter the tracheides, vessels, &c., 

 of the wood, and delignify them, with changes 

 colour and substance as described. Reference mi 

 be made to Prof. Hartig's publications for the detail.' 

 which serve to distinguish histologically between timl 

 attacked by Agaricus melleus and by Trametes or oth( 

 fungi. Enough has been said to show that diagnosis 

 is possible, and indeed, to an expert, not difficult 



It is at least clear from the above sketch that 

 can distinguish these two kinds of diseases of timl 

 and it will be seen on reflection that this depends 

 knowledge of the structure and functions of tl 

 timber and cambium on the one hand, and proj 

 acquaintance with the biology of the fungi on the 

 other. It is the victory of the fungus over the timber 

 in the struggle for existence which brings about the 

 disease ; and one who is ignorant of these points will 

 be apt to go astray in any reasoning which con- 

 cerns the whole question. Any one knowing the facts 

 and understanding their bearings, on the contrary, 

 possesses the key to a reasonable treatment of the 

 timber ; and this is important, because the two 

 diseases referred to can be eradicated from young 

 plantations, and the areas of their ravages limited in 

 older forests. 



