158 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



sion wood with which shghtly narrower cells are associated. The 

 lightwood of 1939, at 29 cm., contains arcs of narrower cells; com- 

 pression wood is associated with one of the arcs. In general, the 

 annuals of 1940 become sharper outward on the branch whereas the 

 intra-annuals become more diffuse. The sharp lens of 1941, at 49 cm., 

 is exterior. Apparently the increment went on to completion in 

 spite of the artificial frost applied outward on the branch May 25, 

 1941, Frost injury is, of course, responsible for the state of 1941 at 

 47 cm. and outward. 



The increment for 1941 gives proof of multiplicity and strongly 

 suggests that the sharp lens was formed after May 25 and before the 

 branch was cut November 29, 1941. 



Table 94. — TTP 24-10 



49 cm. 



1938 I see 



1939 I see 



1940 I see 



I psee 



I dee 



1941 I see 



I sL 



1942 I see 



Branches TTP 24-10 to 24-16 were cut from the tree January i, 

 1943. In the 1940 increment of TTP 24-10 (table 94), the intra- 

 annuals weaken outward to such an extent that they are barely visible 

 at 26 cm. The sharp lens of 1941 is concurrent, interior, and un- 

 doubtedly caused by a late spring frost which is intimately associ- 

 ated with it. At 36 cm. the lens is weak. The intra-annual of 1942 at 

 26 cm. is labeled "growth layer" by reason of the fact that its dense- 

 wood merges with that of the annual for part of the circuit, separates 

 from the annual densewood to make divided densewood for another 

 portion of the circuit, and for 60° is separated sufficiently far to make 

 a lens. 



Branch TTP 24-11 resembles branch 24-10 in many details except 

 that, in 1940, one of the intra-annuals appears as divided densewood 

 rather than as a discrete growth layer. 



