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



87 



the remainder. The divided densewood, or multiple densewood in this 

 case, does not have contacts sufficiently sharp to warrant classification 

 as lenses or intra-annual growth layers. It is rather a transition be- 

 tween multiple growth layers and a unified band of densewood. 



\--ji^-^"-'' •*.•*-'• ■*•* "-' ■"''^■'' 



■.■■•^^>^& 



V^^^^^^#?i^if4^ 



;:••■^^^5**i^;;:;•..:..^:. ;••.... . . 



Fig. 30. — TTC 33-ii-a. Doubly divided densewood (upper figure) in 1940 

 shown by symbol and cell structure, and fading of intra-annuals in the lightwood. 

 Below, on opposite radius, singly divided densewood. 



Such terms as "indistinguishable growth layer" and "low-power" 

 lens may be misleading to be sure, but they serve a useful purpose in 

 emphasizing the complexities, both structural and physiological. To 

 all appearances, the increment for 1940 in TTP 23-4-a is absent 

 around the circuit except in two places where it reveals itself under 

 high power as part of divided densewood of 1939 and as composed of 

 one or two wider cells and one or two narrower cells. This instance 

 comes closest of any in our collection to being a totally absent growth 



