FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 17 



doors were the important agents and that any convection currents 

 formed by the heat of the pileus would be swamped by the natural 

 currents under most conditions. Falck in a later work (16, pp. 226- 

 227) demonstrated how the spores of Merulius lacrymans are scat- 

 tered throughout buildings. He found that a fruit body off in a 

 corner in a church spread spores throughout the edifice and that 

 spores from fruit bodies in a cellar where the temperature was a little 

 higher than that of the rest of the house were carried by air currents 

 to various places in the house. He caught them on glass slides under 

 a bed on a first floor and at places on the second floor. Even a closed 

 door did not keep them out. 



The writer had no opportunity to make extended observations on 

 the dissemination of basidiospores, but several instances came to 

 hand which corroborated in a small way the observations and con- 

 clusions of the above-mentioned authors. Certain observations pre- 

 sented here have to do with the fruiting of Trametes serialis in the 

 fungus pit at Madison, Wis., already referred to. Two fruit bodies 

 of this fungus appeared toward the last of January, 1919. One of 

 them grew at the end of the under side of a horizontal timber. On 

 entering the pit one day it was noticed that the transverse face and 

 a part of the upper surface of the beam were powdered white with 

 a deposit of the spores from the fruit body below (PI. VI, fig. 1). 

 Several similar deposits were noted in November, 1919, when several 

 fruit bodies appeared, most of them on the under side or on the end 

 of another beam. Here were cases in which the spores had been swept 

 directly upward, as if carried by a strong draft from below. But 

 just how there could be strong drafts it is difficult to understand. 

 The pit is sunk 4 feet in the greenhouse floor, walled with concrete, 

 and has a dirt floor and well-fitting covers. There is very little like- 

 lihood of air currents from outside. Glass slides placed beneath the 

 sporophore gathered no spores, but slides placed at points throughout 

 the pit, even at the top near the covers, collected enough spores to be 

 located under the microscope. 



In mills, however, the dissemination of spores is not dependent 

 upon such imperceptible air movements, for considerable air currents 

 arc produced by rapidly moving machinery, sprays from humidifiers, 

 and .steam pipes poorly arranged. These currents become of great 

 importance in distributing spores which may be cast into the air by 

 fruit bodies upon the roof planks. 



Iii the fungus pit on two occasions the opportunity presented 

 itself for observing to what extent insects and other animals may 

 Under certain Conditions disseminate wood-destroying fungi. 'I here 

 i- little literature hearing upon this phase of the subject. One 



occasionally meets with references to Ww connection between wood 



H227H — 22 3 



