168 



Mycologia 



serve serious attention. Neither this rust nor the preceding one 

 has yet been reported from any United States possession. 



The biology of Fonies applanatus is ably and comprehensively 

 treated by J. H. White in the Transactions of the Royal Canadian 

 Institute 12 : 133-174. pi. 2-7. 1919. Two of the most impor- 

 tant results obtained relate to the discharge of spores and to the 

 parasitic nature of the fungus. These are summarized by the 

 author as follows : 



" Spore discharge is enormous and continues for by far the 

 longest period recorded for fungi. It is continuous day and 

 night for about six months — visible from vigorous fruiting 

 bodies as spore clouds. Buller, from a count estimate in the case 

 of Polyporus squamosus, a form which also exhibits spore clouds, 

 concluded that at least 1,700,000 spores were discharged from 

 one tube in three days. A similar calculation with F. applanatus 

 gave the incomprehensible number of 30,000 million spores lib- 

 erated in twenty-four hours from a fruiting body with a pore 

 surface of about one square foot. Discharge is not affected by 

 variations in light, humidity of the air, or temperature within 

 very wide limits ; frost causes an instant cessation and thereafter 

 there is no further spore fall until a new set of pores is organized. 



" Fomes applanatus has been proved to be a wound parasite, 

 arid in southern Ontario at least one of the commonest and most 

 destructive of this type. The proof rests on three grounds: (a) 

 the conventional test applied to other such fungi — the mycelium 

 works upward most readily by the way of the heartwood, causing 

 a characteristic decay and outward into the sapwood, eventually 

 reaching the cambium, and is apparently the cause of the death 

 of the tissues traversed by it; (b) a broad brown band is present 

 in the wood of living trees along the advance line of the invading 

 mycelium of this fungus. Within this band there is a copious 

 production of brown wound gum and an excessive multiplication 

 of tyloses. This band steadily moves forward with the advance- 

 ing hyphae, the tyloses and wound gum being destroyed by the 

 mycelium along its posterior margin as rapidly as they are formed 

 along its anterior edge. The tyloses (and possible the wound 

 gum also) certify to the living condition of the invaded tissues ; 



