176 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



they are inward on the branch ; at 42 cm. two of them are so dim as 

 to be unrecorded in analysis ; at 52 cm. the lightwood of the outer 

 growth layer disappears on one radius. The densewood (dw) at 52 

 cm. is connected with natural frost injury. Tree XSC 12 shows the 

 "outer thin" growth layer of 1939 in striking fashion. The divided 

 densewood becomes a sharp lens outward. In the 1940 increment, 

 all intra-annuals become progressively weaker and more diffuse out- 

 ward on the branch. 



1938 



1939 



1940 



1941 I see mc me inc 



PSg 



XSC 12-2 (table 123) was frozen artificially at 51 cm. on May 9, 

 1941, and was cut off December 6, 1941. In the 1938 increment, the 

 sharp lenses are compound, centering on the same radius inward on 

 the branch but "sliding off" each other outward. The divided dense- 

 wood affects the densewood of the outer lens. In the 1939 increment, 

 the arcs refer to partial bands of densewood scattered throughout the 

 lightwood. In the 1940 increment, the sharp lenses are concurrent. 



XSC 13-1 (table 124) was frozen artificially at 38 cm. on June 14, 

 1941, and was cut off June 20, 1941. In the 1938 increment at 50.5 

 cm., the sharp lens and the divided densewood are one continuous 

 growth layer at the outer margin of the annual increment. They are 

 gone at 38 cm. Although the narrowing of 1938 outward at 27 cm. 

 accounts for the disappearance of some of the intra-annuals, it does 

 not account for the disappearance of all of them. The "outer thin" 

 growth layer of 1939 is striking in tree XSC 13. For a long distance 

 around the circuit, at 38 cm., the densewood of the annual increment 



