22 BULLETIN 101, U. S. DEPARTMENT OF AGRICULTURE. 



The character of penetration in cylinder-treated sticks was similar to that 

 in sticks treated in the penetrance apparatus. The springwood treated longi- 

 tudinally from 1 to 4 or 5 inches, while the summerwood was treated to the 

 center of the stick in nearly every growth ring. 



Practically no difference was noted either in penetration or absorption be- 

 tween the heartwood and sapwood. The average longitudinal penetration was 

 about 90 or 100 times as great as the average radial or tangential penetrations. 



WHITE FIR (ABIES GRANDIS ) . 



The growth rings of white fir were usually very broad, with large and thin- 

 walled springwood tracheids. Resin cells were few and scattering on the outer 

 face of the springwood. Resin passages were not present. Structurally this 

 species is very similar to eastern hemlock. 



The average oven-dry weight per cubic foot of all heart specimens was 22 

 pounds, and of six sap specimens 22.7 pounds. 



The greatest penetration took place in the last-formed summerwood tra- 

 cheids, but the difference was not marked. Near the point of application of 

 pressure both springwood and summerwood were equally treated, and at maxi- 

 mum penetrations even the springwood in many places was heavily treated. 

 The heartwood was slightly easier to penetrate and absorbed somewhat more 

 oil than the sapwood. 



White fir contains no resin structures except simple resin cells, but it was 

 nevertheless penetrated easily in both springwood and summerwood. 



The average longitudinal penetration was about 50 times the average radial 

 and 35 times the average tangential penetration. 



NOBLE FIR (ABIES NOBILIS ) . 



The summerwood of noble fir was about equal in width to the springwood. 

 The spring tracheids were large and thin-walled. In distinct and widely sep- 

 arated growth rings, resin cells were localized to form imperfect resin canals, 

 these occurring in somewhat continuous zones in the summerwood. 



The average oven-dry weight .per cubic foot of 10 heart specimens was 21.9 

 pounds, and of five sap specimens 23.6 pounds. 



The maximum penetration took place along summerwood bands and more 

 especially in the last-formed tracheids of the summerwood. In the most heavily 

 treated zone, near the point of application of pressure, the entire summerwood 

 was treated together with portions of the springwood. 



The character of penetrations in the cylinder and in the penetrance treat- 

 ments were very similar. The summerwood was nearly always treated to the 

 center of the stick. Near the ends considerable springwood penetration was 

 noted. In the sapwood more of the springwood was treated than in the heart- 

 wood. 



The sapwood treated more quickly and absorbed more oil than the heart- 

 wood. Radial and tangential penetrations were of considerable importance, 

 especially in the sapwood. The average longitudinal penetrations were about 

 40 times the average radial and tangential penetrations. 



DOUGLAS FIR (PSEUDOTSTJGA TAXIFOLIA). 



The growth rings of Douglas fir were variable in width. The proportion of 

 summerwood varied from almost nothing to nearly half of the growth ring. 

 The spring tracheids were large and thin-walled. Resin cells were few and 

 were scattered on the outer face of the summerwood. The resin passages were 



