Douglas Fir Fiber 677 



tree number are stated separately in the tables and figure and only 

 the disc and ring designations are given in direct conjunction with 

 the measurements. For example in Figure 1, which refers to ship- 

 ment 2, tree 1, only, the disc designations are given on the left 

 of the diagram and the ring designations at the lower end of the 

 dotted line which marks the course of the particular ring through- 

 out the length of the tree. The chips each included radially one 

 complete year's growth and were about three fourths of an inch 

 long and wide and, of course, the thickness of the annual ring. 

 Each of these samples was split along the plane of the rays into 

 chips with comparatively square ends and thus prepared the set 

 from each annual ring was put into a one-ounce, wide-mouthed 

 bottle filled with an aqueous solution of equal parts of 8 per cent 

 nitric and 8 per cent chromic acids. The outer layers of the 

 chips usually separated into the constituent fibers after not more 

 than three days' treatment, but if not, were treated with fresh 

 acid and heated to not over 50° C. Chips having become suffi- 

 ciently macerated were removed from acid fluid and stored 

 first in distilled water, and secondly in a dilute alcohol solution. 



Method of Examination 



For examination radial slices were removed from one or more 

 chips and the constituent fibers carefully separated out with 

 needles on a glass slide, great care being taken not to break the 

 fibers. The slides thus prepared were placed on a microscope 

 fitted with an eye-piece micrometer and objective of such power 

 that the fibers might be measured directly in millimeters. The 

 adjustment of the microscope was carefully checked, before each 

 slide was measured, with a standard stage micrometer to see that 

 the adjustment had not been accidentally changed. Thus ar 

 ranged, 50 measurements were made from each chip, the fibers 

 being measured without any special choice, except that care was 

 taken not to measure always the longest or the shortest fiber. 



Results of Examination 



Twenty discs, including measurements of 171 annual rings of 

 shipment 2, tree 1, a typical example of coast Douglas fir, were ex- 

 amined. Disc A, the butt end, was two feet from the ground, 

 contained 177 annual rings and was 37.75 inches in diameter, while 

 2-1-L, the top of the log, was 154 feet from the groiuid, contained 



