GROWTH OF THE FUNGUS. 17 



shown at one side. It is surrounded by an intricate mass of hyplu^, 

 in which pieces of undissolved wood are held in much the relative 

 position which they occupied in the sound wood. It will he seen that 

 the wood is practicallv destroved entirelv. The mass of fundus hvv)hie 

 o'ives a soft, leatherv, vieldiiio- consistencv to the rotted material. 



The young hypha^ i\re exceedingly line, so much so that it requires 

 a strong immersion lens to detect them. They are perfectly colorless, 

 and remain so when older. Clamp connection occurs frequently. 



GROWTH OF THE FUNGUS IX BEAD WOOD. 



The mycelium of the fungus grows only in living trunks, so far as 

 could be ascertained. It will grow out from infected wood when the 

 latter is kept in a moist place, but oitlv to a very small extent. A 

 number of pieces of diseased ash trunks, each about a foot long, were 

 placed in the nnishroom cellar of the Missouri Botanical Garden, some 

 with the cut surface in contact with the soil, others exposed to the 

 moist air. In order to test whether dead wood could be infected, 

 several healthy pieces of ash trunks, recently cut and of about the 

 same diameter as the diseased pieces, were placed in contact with the 

 smoothed end surfaces of the diseased pieces. After two or three 

 days the hyphi\? in nearly all the pieces began to grow out from the 

 diseased areas (PI. V), both from the brown areas and from the parts 

 entirely decayed. This indicates that the fungus is equally active all 

 through the diseased parts. In the pieces wherp the cut surfaces were 

 exposed to the moist soil or air the hyphsB grew for some weeks, 

 making a thick, tough felt. They gradually ceased growing after 

 about three weeks. The sound ash trunks were firmly united to the 

 diseased ones after three davs, and after a week the funo-us had ^o 

 thoroughly united the two pieces that they could not be pulled apart, 

 using a moderate amount of force. After three months the healthy 

 pieces were examined. The hyphfe of the fungus had grown into the 

 wood for a very short distance only. They had effected practically 

 no change. A hard cushion of mycelium had formed between the 

 two pieces, and this was turning brown and had evidently ceased 

 growing. These tests show that under the conditions of temperature 

 and moisture which permit of vigorous growth of several of the 

 wood-destroying fungi growing on dead wood the mycelium of the 

 ash fungus will not grow for any length of time. The sound wood 

 placed in contact with the diseased wood was full of starch at the 

 time, so it could not have been lack of food which prevented the 

 growth of the hyphas. A piece was removed from a sporophore 

 immediately after it was brought in from the woods. The sporo- 

 phore remained attached to a section of the trunk about a foot long. 

 For several weeks hyphfe grew out from the injured surface, making 

 a new rounded edge, doing so almost as rapidly as in the natural state. 

 12163— No. 32—03 2 



