36 BULLETIN 275, U. S. DEPARTMENT OF AGRICULTURE . 



A study of the fungi destroying down timber lies beyond the scope 

 of this bulletin. The only practical aspect of their activity lies in the 

 fact that down timber, limbs, branches, twigs, and needles are decom- 

 posed very rapidly. 



It is evident that all the points discussed in the preceding pages 

 must be kept in mind in taking field notes. But this is not sufficient. 

 Work of this kind has very much the character of an exploration; 

 surprises and discoveries are possible at any point Of the road, and it 

 is therefore indispensable constantly to be on guard in order not to 

 overlook any phenomenon worthy of observation. 



TABULATION OF DATA. 



The next step is proper tabulation of the data obtained. The three 

 tracts were so close together and conditions so similar that they were 

 considered as one, and all notes were combined. Separate interpreta- 

 tion of the notes of each tract showed differences only in detail. The 

 procedure was as follows: 



A first table was compiled from the field notes giving all important 

 data as well as all such data' which might have a bearing on the 

 subject of this bulletin. As we are particularly interested in the 

 problem of the relation of age to infection and subsequent decay, a 

 second table gave the same notes arranged progressively by the ages 

 of the trees examined. This table formed the basis for further 

 operations. 



The youngest tree dissected was 60 years old, and it is the first to 

 show decay (Table I). The possible age limit of infection is therefore 

 at least 60 years; it is probably lower. But in practical forestry we 

 do not seek an answer to the question of the earliest age at which a 

 tree might become infected, interesting as this is from a mycological 

 point of view, but, rather, from what age may we with reasonable 

 certainty assume that serious decay becomes so prevalent as to 

 distinctly impair the merchantability of the timber. 



The tree in question has a diameter breast high of 10.1 inches; it is 

 44 feet high. A healed-over broad scar still visible externally at 2 to 

 8 feet above ground corresponds to an internal scar, reaching from 2 

 to 10 feet, and was probably caused by hghtning. The injury happened 

 22 years ago and was distinctly superficial: the deterioration, in the 

 form of a slight discoloration of the sapwood, follows this scar only, 

 without extending any farther into the wood. This superficial dam- 

 age does not render the affected logs unmerchantable. For practical 

 purposes, therefore, such cases may be disregarded; they are negli- 

 gible. In the interpretation of our material, the character and the 

 degree of the damage must be considered with special relation to their 

 bearing on the merchantability of the lumber. Not only the extent 

 in longitudinal direction but also the distribution of the decay over 



