472 RESEARCHES ON FUNGI 



confined to the gills ; but, in our morchelloid pileus, it not only 

 covers the gills, but also lines the outer surfaces of all the alveoU 

 on the top of the pileus. 



The cause of the morchelloid development of the pileus in 

 Legue's Collybia velutipes fruit-bodies is as much a mystery as the 

 cause of the occasional tremelloid development of the pileus and 

 stipe in fruit-bodies of C. dryophila. ; but, here again, we are pro- 



FiG. 195. — Collybia velutipes, a morchelloid form observed in France. The 

 alveolate upper surface of the pileus, Uke the gills, is covered with 

 a fertile hymenium. Photographed by the late L. Legue. Natural 

 size. 



vided with evidence of remarkable plasticity in a species which 

 normally varies within very narrow limits. ^ 



Another teratological form of Collybia velutipes was found in 

 the State of New York by Stewart ^ in 1911. " The malformation," 

 says Stewart, " was one affecting the gills. Instead of being straight 

 and even in the edge like a knife-blade, as is the case with normal 

 gills, they were irregular and double-edged, with numerous lateral 

 projections and a strong tendency to anastomose." Three of the 



1 Collybia vehitipes is not the only agaric which occasionally develops in a morchel- 

 loid manner. Thus morchelloid forms of certain Cortinarii have been described 

 by Boudier {Biill. Soc. Myc. Fr., T. VI, p. 169 and Plate XVIII) and by Dumee 

 and Lutz {Ibid., T. XVIII, p. 131). 



2 F. C. Stewart, The Velvet-stemmed Collybia — a Wild Winter Mushroom, Bull, 

 no. 448, New York Agri. Exp. Station, 1918, p. 83. 



