CHROMOGENIC FUNGI WHICH DISCOLOR WOOD. 109 



slightly resembles the conidia of Cephalothecium (pi. 12, 

 f. 3). 



The microconidia are oval to elliptical in shape, varying 

 in length from 8/x to 14.5/1, and in diameter from 3/* to 6/i. 

 They are hyaline, colorless, thin walled, and are usually 

 uninucleate. Many are slightly curved. 



Macroconidia. 



The macroconidia are of the Fusarium type, and vary 

 considerably in shape and size. They are usually formed 

 by abstriction of the ends of short, swollen, branching 

 hyphae, and are from two- to four-celled, straight or 

 curved, with tapering, rather blunt ends, varying in length 

 from 19/Lt to 30/x, and in diameter from 3.5/i to 6^. Both 

 microconidia and macroconidia germinate readily on all 

 ordinary agar culture media, the time varying with the 

 medium. The macroconidia are rarely found attached to 

 the hyphae when fully mature. 



Chlamydospores. 



Both terminal and intercalary chlamydospores are 

 formed singly or several in series (pi. 12, f. 6, 8, 9). They 

 are formed by the enlargement of the cells of the mycelial 

 filaments. Their development is more gradual than that 

 of the conidia, and the cell wall is much thicker. In shape 

 they are spherical, or slightly oval. The cell contents are 

 granular, and vary in color from yellow to dark brown. 

 The diameter of the spores averages 12/x. When the 

 macroconidia start to germinate, and are hindered by a sud- 

 den drying out, or other adverse conditions, it is not unus- 

 ual for one of the cells to form a chlamydospore (pi. 12, 

 f. 5); these are rarely mature, and have never been 

 observed to germinate. 



SCLKROTIA. 



Sclerotia are produced in cultures on boiled potato and 



