THE "blue" fungus. 25 



the hyphiv and fruitiii*:- bodies of the fungus. The green matter, 

 xylindeine, is confined to the fungus threads and in no way stains the 

 wood til)ers. Vuilleniin states expressly (p. 144) tliat "there is no 

 green decay or green staining of the wood. The wood appears green 

 when the colored thallus of UAothnn xrmjinosum or of analogous 

 fungi is found in its elements." With the highest powers of the 

 microscope he was unable to tind any coloration of the walls of the 

 wood. The green color is therefore due to the presence en masse of 

 green -colored threads. 



Similar instances of color due to the presence of colored mycelium 

 are found on pine and spruce wood, where brown and black lines are 

 formed by masses of dark hypha' bunched at particular points in the 

 wood cells. The familiar zigzag and fantastic lines often found in 

 wood of the tulip tree and in birch and maple are due to similar fungus 

 threads. In none of these cases are the wood fibers themselves colored. 



So far as known to the writer, no attempt has ever been made to 

 explain the nature of the blue color of coniferous woods. The color 

 is a difficult one to define. A number of the writer's artist friends 

 who were called into consultation pronounced it a blue gray, approach- 

 ing Payne's gray. Freshly cut wood looks decidedly blue, but as the 

 wood dries the color fades somewhat and dry wood is mouse gray. 

 The color is by no means regular; here and there some of the yellow 

 of the healthy wood shines through. The drawing shown on PI. I is 

 perhaps a little too blue. PI. V is closer to the real color. Certain 

 portions of the blued wood look greenish when viewed obliquely. 



There are two possible explanations as to the cause of the so-called 

 blue color: (1) The wood may appear colored because of the pres- 

 ence of the colored fungus threads in the wood. The mass efiect of 

 such colored threads might make the wood appear colored. (2) The 

 wood might be colored by a pigment or stain formed either })y the 

 fungus or as a result of the fungus growth in the wood, and this 

 pigment might stain the walls of the wood fibers. 



The first explanation holds good for the "green" wood. Here a 

 pigment is formed in the hyphae and fruiting Iwdies of the fungus, and 

 it is because of the presence of the green-colored bodies in the fungus 

 threads, according to Vuillemin, that the entire wood looks green. 

 Careful examinations made of the "blue" wood by persons trained to 

 observe colors, called into consultation by the writer, have led to some- 

 what conflicting results, and it is therefore thought inadvisable in the 

 present stage of the investigation to enter on a lengthy discussion of 

 the color subject. A number of facts may be stated, however. Exam- 

 inations of the wood fibers of sound and "blue" wood showed that it 

 was possible in most instances to distinguish between the sound and 

 the "blue" wood. The walls of the sound wood look somewhat 

 darker (with a suggestion of purple) than the blued fiber. This method 



