FOREST PATHOLOGY IN FOREST REGULATION. 27 



mating should be reduced to a minimum. In order to render this 

 unavoidable minimum, which undoubtedly constitutes a source of 

 error, as innocuous as possible, the operator must constantly be on 

 the guard against any variations of his standard by which he is guided, 

 consciously or subconsciously, and from time to time check up on 

 this standard. The notes to be taken by estimate concern degree 

 or grade. Soil moisture, seriousness of wounding by fire, degree of 

 resin flow (whether light or heavy), condition of crown (for example, 

 unhealthy color or thin foliage and the presence and degree of needle 

 diseases in. their bearing on the thriftiness of the tree), degree of dis- 

 coloration of the wood — all these can be expressed in figures only 

 with difficulty. Even if a scale of 1 to 10 is adopted for these pur- 

 poses it is extremely difficult to decide whether the change of color 

 of the wood under the influence of the fungus is to be classed as 6 or 7. 

 The writer therefore has adopted a simpler system, which, while far 

 from being exact, at least avoids gross errors and at the same time is 

 graphically clear and sufficiently elastic to cover all cases of impor- 

 tance. It expresses the information asked for on the sheets with the 

 aid of crosses and dashes. A dash after "Fire scars," for instance, 

 is negative; there is no fire scar. One cross, x, is simply affirmative; 

 there is fire injury, but it is not to be considered as serious. Two 

 crosses, xx, indicate that the fire injury is fairly bad, distinctly 

 beyond the mere presence of an injury. Three crosses, xxx, em- 

 phasize the damage; the fire injury is unusually large and severe. By 

 putting the crosses in parentheses, (x), or x (x), or by hyphenating two 

 consecutive degrees, x-xx, intermediate grades may be given when 

 desirable; and finally the last grade, xxxx, can be used in very extraor- 

 dinary cases for emphasis. In general, x, xx, and xxx will answer the 

 purpose. Thus, the estimate is really reduced to a simple system of 

 three grades, which allows for a more constant mental reference to 

 the standard. Whenever necessary or feasible, special notes or meas- 

 urements are entered after the crosses. This system is also used in 

 our tables. With the exception given above, all these notes are 

 taken by the chief of the party. Meantime, the assistant counts the 

 age and diameter at every cross section, takes growth measurements, 

 measures the width of sapwood and the length of the sections, and 

 records such other data as may present themselves in the course of 

 the work. 



In complicated cases, drawings or notes are added on blank sheets 

 bearing the numbers of the trees. 



PATHOLOGY OF WHITE FIR. 



The studies on white fir presented in the following pages are not 

 meant to give definite results valid for the entire range of the species. 

 They were primarily intended to develop the more practical methods 



