CHROMOGENIC FUNGI WHICH DISCOLOR WOOD. 63 



conidia in their descriptions is very limited indeed, only 

 two being noted, and where such descriptions have been 

 given, no mention is made of the connection between the 

 conidial and the perfect or perithecial stages as being 

 established by cultural methods. For instance, Ceratos- 

 tomellaalbocoronata (Ellis) Sacc. has a conidial stage where 

 the conidia are from 2- to 3-septate, and of abnormally 

 large size. So far as our investigation has proceeded, all 

 species of Ceratostomella have colorless conidia, that are 

 one-celled and of about the same measurements as the 

 ascospores. The presence of asci in the perithecia has 

 been the most difficult point to prove. Cultures must be 

 taken at the stage just preceding full maturity of the ascus, 

 else it apparently dissolves and frees the ascospores at ma- 

 turity, allowing their free ejection through the long, nar- 

 row beak of the perithecium, but destroying the evidence 

 of the presence of a sac. In an examination of the ejected 

 ascospores they are frequently found adhering to each 

 other in fours, side by side, in the same position they 

 occupied in the ascus. 



The conidial stage of Ceratostomella is very important, 

 owing to the immense number of conidia borne on the 

 mycelium in its earlier growth. These are readily dissem- 

 inated by the wind and are probably carried by insects 

 which penetrate the wood and bark of trees, like most of 

 the ambrosia and bark beetles. At the stage in which the 

 conidia form a mucilaginous mass, they adhere readily to 

 any insect that may pass over them. In the laboratory a 

 number of species of mites which feed on fungi carried 

 spores on their bodies from a colony in an agar plate to a 

 sterile portion of the surface of the medium and started 

 new colonies of the fungus. Bark beetles were placed in 

 a dish with the conidial stage of Ceratostomella, and after 

 allowing them to remain a short time were transferred to 

 sterile agar plates which were inoculated with spores 

 from the insects. It is probable that some species of in- 



