CHKOMOGENIC FUNGI WHICH DISCOLOR WOOD. 65 



trates rapidly the sap wood of dead and dying trees, giving 

 it a peculiar blue tint whose color is hard to explain, since 

 the mycelium of the fungus in the cells of the wood is a 

 dark brown. It has also been found in the sapwood of 

 species of Abies, Qitercus, Fraxinus, and other genera. 



Ceratostomella pilifera grows readily upon a large num- 

 ber of culture media. Pine decoction agar made from the 

 bark and sapwood was found an excellent medium for its 

 cultivation. Two distinct fruiting forms were observed in 

 all the varieties, the conidial and the perfect or perithecial. 



Mycelium. 



"When either the conidia or ascospores are sown in pine 

 agar plates, germination takes place in a few hours, and in 

 two days colonies with a white hyaline mycelium develop. 

 The filaments are septate, and, as a rule, branch alternately. 

 In a day or so upright hyphae, either simple or branched, 

 are sent out, upon which are borne branching whorls of 

 conidia. In the course of a week or so, portions of the 

 mycelium in the older region of the colonies develop with 

 thicker walls and assume a brown color. From these dark 

 colored filaments the perithecia originate. 



The first growth of the mycelium is usually sparse, 

 but under favorable conditions a secondary profuse 

 growth with a fluffy white appearance develops, which 

 bears conidia, and the formation of perithecia is retarded. 

 Such a growth is formed on some of the richer media 

 made from pine and other plant decoctions. Under these 

 conditions the development of conidia is enormous, and 

 the number of perithecia is decreased somewhat. Cultures 

 on the sapwood of trees in test tubes bear both stages of 

 the fungus abundantly. On the heartwood, however, but 

 few conidia are formed, the mycelium is almost invisible to 

 the eye, and perithecia are either sparse or entirely absent. 

 The filaments of the fungus never penetrate deeply into 



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