172 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



complete, entire growth layer of 1939 is somewhat obscure because it 

 is thin and because its densewood is a very thin thread. The growth 

 layers of 1939, other than the two sharp, complete, entire growth 

 layers, are becoming highly diffuse and disappearing at 33.5 cm. At 

 48.5 cm. a diffuse lens barely begins, a lens quite plainly visible out 

 at 42.5 cm. but entirely gone at 33.5 cm. 



Table 116.— XSC 9-5 

 52.5 cm. 48.5 cm. 42.5 cm. 33.5 cm. 



1937 I see I see i see 



I psce I dee 



1938 I see I see i see i see 



I psee 



I dee 2 dee 3 dee 3 dee 



I sL I sL I sL I dee 



1939 2 see 2 see 2 see 2 see 



I msL I msL i msL 



1 dL 



1940 2 see 2 see 2 see 2 see 



I sL I sL 



2 sL I sL 



ddw 



1941 I see I pee inc ine 



psg 



Under low power one of the sharp, complete, entire growth layers 

 of 1940 is actually divided densewood which broadens outward on the 

 branch. At 48.5 cm. the short, sharp lens of 52.5 cm. has narrowed 

 down until it is merely divided densewood ; at 42.5 cm. a new lens 

 system appears, a compound lens of two members, one of which nar- 

 rows at 33.5 cm. to divided densewood. 



XSC 9-6 (table 117) was frozen artificially May 9, 1941, and was 

 cut off June 27, 1941. In the 1938 increment, the mostly sharp, com- 

 plete, entire growth layer and the diffuse, complete, entire growth layer 

 become more diffuse outward from 46 cm., so much so that they have 

 practically disappeared at 29 cm. In 1939 the diffuse lens weakens out- 

 ward to faintness at 40 and 29 cm. In 1940 one of the sharp, com- 

 plete, entire growth layers at 52 cm. is sufficiently narrow to be classed 

 perhaps as divided densewood. At 46, 40, and 29 cm, it is the diffuse 

 portion of the mostly sharp, complete, entire growth layer which has 

 the divided densewood. The two sharp lenses are equivalent to one 

 compound lens whose borders become slightly less definite outward. 



XSC lo-i (table 118) was frozen artificially at 34.5 cm. on May 9, 



