6 BULLETIlSr 1037, V. S. DEPARTMENT OF AGRICULTUEE. 



He found that when 1 by 3 by 6 inch boards of alder {Alnus incana 

 Moench), white or gray birch {Betula popuUfolia Marsh), paper 

 birch {Betula papyrifera Marsh), and various trees belonging to the 

 rose famil}^ (Rosacese) were immersed in boiling water and then 

 stacked under cover they would remain unchanged in color. Those 

 boards which had been immersed in the boiling water and then 

 placed in the most unfavorable conditions of high humidity and 

 temperature in the open and exposed to the direct rays of the sun 

 scorched on the surface. With the exception of this superficial 

 scorching, no discoloration of the wood took place. On the other 

 hand, untreated boards that had been cut from the same portion of 

 the tree and subjected to similar conditions of temperature and 

 humidity stained rapidly. Bailey {5) found that the rapidity and 

 the depth to which the stain penetrates the wood varies with the 

 temperature and the moisture, hot and humid weather being espe- 

 cially favorable for the production of stain. From a consideration 

 of the results obtained, he concludes that sap-stain caused by oxidiz- 

 ing enzyms can be readily prevented by dipping the timber for a few 

 minutes in boiling water. 



Though chemical stains give more or less trouble in kiln-dried 

 maple flooring and sugar-pine lumber, the discolorations may bo 

 prevented to an extent by the use of comparatively low temperatures 

 (120° to 125° F.) and correspondingly low humidities (50 to TO per 

 cent; Tiemann, 51^ p. 185). Becnuse of their limited distribution 

 and the fact that they do not imjDair the strength or durability of the 

 timber, chemical stains in general can hardly be considered as having 

 very. great economic importance. 



FUNGOUS GTAINS. 



The second class of stains is produced by fungi. These fungi are 

 disseminated by means of minute bodies known as spores. The 

 spores may be produced in countless numbers and are blown about 

 by the wind, washed along by the rain, or carried by animals, 

 particularly insects. When, under favorable humidity and tem- 

 perature conditions, they happen to lodge upon a substratum, such 

 as the moist green sapwood of woods that contain the requisite food 

 material, the spores may germinate and give rise to a mass of fine, 

 usually septate threads, sometimes colorless at first, but often becom- 

 ing darkened with age. This vegetative portion of the fungus is 

 known as the mjcelium, and the individual threads are called hyphoe. 

 In some cases the hyphse probably penetrate the wood but little, 

 growing for the most part over the surface ; in others, they may enter 

 the sapwood through the medullary or pith rays. This does not result 

 in the disintegration of the walls of the wood cells to any appreciable 



