24 TIMBEE EOT CAUSED BY LENZITES SEPIAEIA. 



tissues as in the healthy ones. Carbazol with hydrocliloric acid 

 gives a violet red, deeper in the rotted than in the normal wood. 



These tests seem to show that tlie fungus has extracted or disor- 

 ganized the coniferin and the hadromal of the lignin, but has left the 

 vanillin. 



PROOF THAT LENZITES SEPIARIA CAUSES THE DECAY. 



Every indication noted in the field showed that tliis fungus causes 

 the peculiar form of dry rot which has been attributed to it. The 

 sporophores are located so near the badly decayed places in the wood 

 that there seems to be no doubt of the connection of the two. But 

 this is far from accurate scientific proof. Artificial inoculations made 

 by the writer in freshly felled sound green trees have gone far 

 toward furnisliing such proof. A fragment of rotted wood was used 

 for inoculating material, being placed in a small hole bored in the 

 side of the tree; the hole was then plugged with a piece of green wood 

 cut from the same tree, and about 3 inches long. When cut open, 

 five months later, it was found that the plug was badly rotted m the 

 middle tlu"ough its entire length, while the inoculating material 

 touched it at the inner end, and on the outer end was a small but 

 mature sporophore. (PI. Ill, fig. 2.) Besides this, the writer has 

 repeatedly grown pure cultures of Lenzites sepiaria upon sterilized 

 wood blocks and has obtained in these cultures the same type of 

 brown dry rot that is constantly associated with the fungus in the 

 open air. (PI. IV.) 



FACTORS GOVERNING THE GROWTH OF WOOD-ROTTING FUNGI. 



It is a matter of general knowledge among botanists that there 

 are certain definite factors wliich control the growth and reproduc- 

 tion of the higher fungi. The more important of these factors may 

 be called food, air, water, and temperature. 



It may be said by way of summary that if any one of these 

 factors is unfavorable, the wood-rottmg fungi can not live any great 

 length of time and can not grow at all. 



Food materials. — Suitable nutritive materials are as essential to 

 the existence of the fungi as they are for any other living organism. 

 The food of the wood-rotting fungi consists of two classes of material, 

 the contents of the wood cells and the wood cell walls themselves. 

 The former consist of a very heterogeneous group of substances, such 

 as starch, oil, protoplasm, tarmin, sugar, minerals in soluble form, 

 pitch, resin, crystals, etc. The wood-cell walls consist of a cellulose 

 base or framework, with various laminae strengthened with lignin, 

 both substances being of a very complex nature. The wood-inhabit- 

 ing fungi attack these various substances with great variability; 



214 



