CHEOMOGENIC FUNGI WHICH DISCOLOR WOOD. 93 



wood of lumber made from Quercus rubra L. in Indiana. 

 This, when isolated in pure cultures, grew readily on the 

 sapwood of pine, oak, gum and ash, and on vegetable agar 

 media, also on potato, bean, and other vegetables in test 

 tubes. The fungus corresponds quite closely to the de- 

 scription of Graphium rigidnm (Pers.) Sacc, with the 

 exception that it has in addition a conidial stage, the coni- 

 dial clusters taking the closed form. The following 

 emended description of this species is now given from 

 artificial cultures on wood and agar media : — 



Mycelium. 



Cultures of both primary and secondary conidia sown in 

 ordinary vegetable agar media germinate in a few hours, 

 and in two days begin to bear an abundant crop of 

 secondary conidia in clusters of a type similar to those 

 of G. smaragdinwn, which collect as rapidly as they de- 

 velop into rounded, mucilaginous clusters (pi. 7, f, 7). 

 The filaments of the mycelium are hyaline at first, but in a 

 few days form a brown pigment in the older portion, and 

 throw up stalked heads bearing the primary conidia. These 

 vary from a stalk consisting of two or three filaments with 

 a small globular or flattened oval head, to one consisting of 

 many, with a much larger head (pi. 7, f. 6). 



Secondary Conidia. 



Secondary conidia are borne on both simple and branch- 

 ing hyphae by abstriction of the ends, and as fast as they 

 are formed adhere together in masses resembling Cephalo- 

 sporium. Theyare colorless, thin -walled, and are usually 

 free from guttules and granules. They measure 3/a to 

 4.5/a by Ifi to 1.5/u. (pi. 7, f. 8). 



