MUKRILL : POLVPORACEAE OF NORTH AMERICA 111 



This plant is one of the oldest fungi known, having been used 

 from very early times for keeping fire, whence the name. It is 

 also abundant and widely distributed, occurring on birch, willow, 

 beech, maple, oak, poplar, apple and many other deciduous trees 

 in various parts of the world. F'ruit-bodies observed on apple, 

 willow, aspen, birch, etc., in Sweden, agree perfectly with those 

 growing in the New York forests ; while the variations found in 

 Europe arc duplicated here, even to the abundance or scarcity of 

 spines in the hymenium. 



Specimens are to be found in all published exsiccati bearing 

 upon this group. Among the large number of collections exam- 

 ined, the following may be mentioned : New York (Underwood), 

 New Hampshire (Miss Minns), Ottawa, Canada (Macoun), New 

 Jersey (Ellis), Virginia (Murrill), Kansas (Bartholomew), Indiana 

 (Underwood), Colorado (Earle), Labrador (Waghorne), Maine 

 (Ricker), New Mexico (Earle), Finland (Karsten), Sweden (Murrill), 

 Thiiringen (Underwood). 



Two forms of P. igniarms are listed as distinct species in Sac- 

 cardo's Sylloge, /. c. Fames badius Berk, and Fomes nigricans 

 Fries. The former was collected in Arctic North America by Dr. 

 Richardson and the type is at Kew. The specimen is 5 X 6 X 

 2.5 cm. and has three layers of tubes which, in the brief northern 

 season, were forced to develop quickly and are therefore thinner- 

 walled than in our forms. Berkeley himself doubted if the plants 

 were sufficiently distinct from P. igniarius. 



Fames nigricans Fries, on the other hand, is decidedly different 

 from typical P. igniarius, being neat and smooth and shining black, 

 and rimose in two directions when old. Fries observed it on birch 

 only. Persoon noticed it also frequently on old willows, and 

 Underwood has collected fine specimens of the same form on 

 beech in the New York mountains. While studying living plants 

 on willov/ trees in Sweden, I found stages on the same tree con- 

 necting this variety with the typical form and am convinced that 

 we are not here dealing with two distinct plants but with varia- 

 tions due to season, food supply, rapidity of growth, or some other 

 physiological cause yet to be determined. Specimens have been 

 examined from F"inland (Karsten, Starback), Sweden (Romell, 

 Murrill), Newfoundland (Waghorne), Greenland (Rostrup), New 



