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JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



are carried by subterranean animals from one place to another ; 

 moreover, the matter has become more complex since Brefeld 

 discovered the second form of conidial spores. Of course the 

 fructifications should be destroyed by burning, as also the dead 

 and dying branches, stumps, &c. Hartig has found that moats, 

 dug so as to cut off sound trees from infected ones, have been of 

 service. 



Agaricus melleus, though a less pronounced parasite, is not 

 less destructive ; the details of its action on the timber are 

 different, and its mode of spreading from root to root in the soil, 

 by means of its long, purple-black, cord-like mycelial strands, 

 called Bhizo7noiylia, also differs. But the net results are much 

 the same in both cases. Very tangible signs of the presence of 

 Agaricus melleus, in the absence of the tawny yellow "toad- 

 stools," are afforded by the copious outflow of resin from the 

 diseased roots and base of the stem of the affected trees, and by 

 the above rhizomorphs in the rotting wood and soil around. 



Most of the Polypori mentioned are decidedly wound-fungi — 

 that is to say, they only attack successfully those parts of the 

 timber which are already dead and exposed to the air ; their in- 

 fluence for evil should not be underrated on that account, 

 however, for although they are saprophytes living on the wood, 

 their entrance into the trunk and branches means more or less 

 rapid hollowing of the heart -wood (thereby rendering the tree 

 liable to be thrown by winds, &c.) and the gradual production 

 of injurious substances which soak into the sound parts and 

 pave the way for the advance of the destroying mycelium into 

 living organs. Hence, though such fungi are saprophytes, 

 strictly speaking, in their local action, they nevertheless act to- 

 wards the whole tree — taken as a living individual — as parasites 

 which may induce dangerous diseases. 



Eemedial measures are of course to be directed to the 

 careful tending and covering of wounds, a mode of procedure 

 which has long been carried out on various trees at Kew, and 

 with decided success, I believe. 



A complete list of the fungi known to produce diseases in 

 Pines would be a formidable affair in itself, and would include 

 a large number of Ascomycetes, of which some, recently investi- 

 gated, are very curious and interesting in themselves. 



I have already spoken of Hystcrium Pinastri as the cause 



