NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL, I39 



be described from tree TTC 34. The 1940 increment commonly 

 contains two sharp, complete, entire growth layers. Because of the 

 cutting date, July 28, 1942, and the impact of artificial freezing, 1942 

 may be incomplete. In the 1942 increment of TTC 34-11 (table 60), 

 the postseasonal growth at 43.5 cm. consists of a few cells scattered 

 around the circuit outside the completed growth layer and beneath 

 the cambium. At 30.5 cm. the postseasonal growth consists of one 

 long, incomplete lens made up of one to five rows of large, immature, 

 lightwood cells. The entire growth layer, which at 43.5 cm. is com- 

 plete and sharply bordered, has a portion of its band of densewood 

 composed of large cells that lack a sharp border on the outside. Here 

 we see the formation of what later would be called a partly sharp, 

 partly diffuse growth layer or a mostly sharp, complete, entire growth 

 layer. Outward on the branch at 21.5 cm. no densewood had been 

 formed by July 28. Growth which was divided into two diameter 

 flushes inward on the branch was combined into one flush outward. 



Table 61.— TTC 34-26 



54.5 cm 42.5 cm. 34 cm. 



1940 I see 



1941 I see I see i see 



1942 2 psce 2 psce 3 dee 



inc inc inc 



Branch TTC 34-26 (table 61) was cut from the tree July 28, 1942. 

 At 54.5 cm. the number of sharp contacts varies on different radii 

 from two to four. Among the intra-annuals of 1942, at 42.5 cm., the 

 sharp portion of one parallels the diffuse portion of the other. The 

 total increment of 1942 becomes thicker outward on the branch. Arti- 

 ficial frost was applied to the branch on May 29 at the time the 

 incomplete growth layer was being formed. 



1944 



Specimens TTC 35-2, 4, and 8 (tables 62-64) were cut from the 

 tree July 31, 1944. Contacts increase in diffuseness outward on the 

 branches, and the incomplete growth layers are in the nature of post- 

 seasonal growth. 



