JL4 BULLETIN 191 



' VII. EFFECT OF THE FUNGUS ON THE WOOD 



The change from the natural color of the wood to a red brown has 

 been responsible for the name of "red rot" lumber, by which woods- 

 men and lumbermen designate the diseased wood. 



Breaking and crushing strength tests. In order to show the ex- 

 tent to which the changes wrought by the fungus as outlined on pages 

 7 to 10 take place, and to afford a comparison of diseased and healthy 

 wood from the standpoint of the Tise of lumber for manufacturing pur- 

 poses, tests of breaking and crushing strengths were carried out as 

 follows : A complete section of a diseased pine log about 12 inches 

 long was taken from a standing tree in Bradford. This tree was 

 about eight inches in diameter and about 35 feet high. A fruiting body 

 was found at a knot-hole four and one-half feet from the ground. A 

 cross sectional photograph (Plate I) indicates the extent to which the 

 fungus had penetrated the wood. This 12-inch section was seasoned in 

 a boiler-room where it was subjected approximately to the heat em- 

 ployed in an ordinary kiln-drying process. The log then was sawed 

 as economically as possible into sticks with an average measurement 

 of 1.1 x 1.2 x 10 inches. These sticks were assorted then into three 

 classes, according to the extent to which the fungus was present in 

 each, as follows: 



(1) Showing very little or no evidence of disease. 



(2) Fungus growth on one or two sides. 



(3) Thoroughly ramified by the fungus. 



The weight of each stick and its volume by displacement of water 

 were obtained. Breaking strengths were determined on sticks ten inches 

 long and crushing strengths were determined on five-inch lengths. 1 

 Four sets of tests were conducted for each class. A summation of re- 

 sults follows: 



SUMMARY OF TESTS FOR THE THREE CLASSES 



This table is self explanatory. It shows plainly the relative de- 

 .crease in weight and in breaking and crushing strengths proportional 

 to the extent to which the fungus had penetrated. 



1 The strength tests were carried out in the College of Engineering under the 

 direction of J. O. Draffin of the Class of 1913. 



