40 



show bow rapidly it spreads, nor whether the characteristic form of 

 decav which it induces continues in wood after it has been cut from 

 a tree or not. The present view seems to indicate that it does not 

 grow after the death of the tree. 



HYZNIEyiUM. 



Hartig ^ has given a very full description and numerous drawings 

 of the hymenial layer of this fungus, and his observations can simply 

 be confirmed. The basidia arise as slender hyph^, which gradually 

 become much smaller at the apex and form four slender, rather long 

 sterigmata. bearing the spores. These are colorless at first, but turn 

 brown later on, and not infrequently contain an oil globule in the 

 center. The most striking elements of the hymenial layer are the 

 cystidia. called hairs by Hartig. They arise from internal hypha?. 

 which approach the hymenial layer at an angle. Pushing between the 

 basidia and paraphyses one finds these large, pointed, brown, spine- 

 like bodies, which project for a considerable distance into the pore 

 canal (PL IX. figs. '2 and 3). They are thick walled and persist for a 

 long time after the disappearance of the basidia and spores. 



As the pores grow older they are filled with a network of hyph?e 

 which grow out from the body of the sporophore. growing over the 

 hymenial layer and completely plugging the hole. The exact period 

 when this takes place was not determined. 



POLYPORUS SULFUREUS (BuU.) Fr. 

 OCCURREXCE. 



This fungus, although more frequently found on the hardwood trees, 

 occurs now and then on living Spruces and brings about a brown rot 

 of the wood of trunk and branches. The trees found were attacked 

 after the trunks were 9 inches (23^°^.) in diameter. Entrance is effected 

 through wounds and broken branches, much in the same way as the 

 other parasitic fungi which enter above the ground. The mycelium 

 spreads through the trunk of an affected tree, growing up and down, 

 and reaching the highest branches in one direction and the roots in 

 the other. Xo e^'idence of a diseased condition is usually visible on 

 the outside, except such as noted for the other diseases. 



STRUCTURE OF DISEASED WOOD. 



Diseased wood is red-brown in color and can readily be distinguished 

 from wood changed by the other fungi described by the fact that it 

 breaks into slabs or flat pieces, which correspond each to an annual 

 ring of wood (PL XIII). The brown rotted wood is hard, very brittle, 



^ Hartig, R. Wichtige Krankheiten der Waldbiiiime. 50. pi. 3. 1874. 



