NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. 189 



zones, the inner of 8.8 cm. and the outer of 3.5 cm. No terminal bud 

 scale scars and no lateral buds marked the separation between the two 

 sets. A section taken from the inner needle zone contains i see only. 



TTP 24-12 comprised the inner part and TTP 24-23 the outer part 

 of a single branch cut off January i, 1943. In the tip growth for 

 1941, the inner set of bare-needle zones measured 5.4 cm. and the 

 outer 3 cm. In the tip growth for 1942, the inner set measured 6.3 

 cm. and the outer 3 cm. Terminal bud scale scars separated the two 

 annual flushes whereas a small branch emerged from the base of the 

 outer bare zone of 1941, and pistillate cones emerged from the like 

 place of 1942. In 1942, total tip growth had been essentially completed 

 by May 16. 



Sections a, TTP 24-12, 53.5 cm. from tip of terminal bud, in 1937 

 tip flush, show I see each for 1941 and 1942. 



Sections b, 40 cm. from tip, in 1938 tip flush, show i see for 1941 

 and I see plus i psce for 19^42. In fact, the psce actually grades into 

 ddw on one arc. 



Sections c, 30.5 cm. from tip, in 1939 tip flush, show i see for 1941 

 and I see plus i dee for 1942. 



Therefore, 1941 contains one growth layer for two sets of bare- 

 needle zones whereas 1942 contains two growth layers for two sets. 



Sections a of TTP 24-23, 15.2 cm. from base of terminal bud, in 

 inner needle zone of 1941, contain i see for 1941 and i see for 1942. 



Sections b, 10.8 cm. from base of terminal bud, in outer needle zone 

 of 1941, contain i see for 1941 and i see plus psg for 1942. 



Sections c, 4.4 cm. from base of terminal bud, in inner needle zone 

 of 1942, contain i see plus psg. 



Sections d, 1.5 cm. from base of terminal bud, in outer needle zone 

 of 1942, contain i see plus concurrent, exterior, sharp half-lenses. 



Here, in contrast with TTP 20-21, multiple diameter flushes for 

 multiple sets of bare-needle zones are present inward on a branch and 

 absent outward near the tip. 



TTP 24-13 comprised the inner part and TTP 24-24 the outer part 

 of a single branch cut off January i, 1943. The inner set of bare- 

 needle zones of 1941 tip growth measured 6.1 cm. and the outer 1.7 

 cm. For 1942 tip growth, the respective measurements were 6.8 cm. 

 and 2.3 cm. with a terminal bud of 1.7 cm. Terminal bud scale scars 

 separated the two annual flushes, whereas two branches came out from 

 the base of the outer bare zone of 1941, two came out from the outer 

 end of 1941, and two buds were present at the base of the outer bare 

 zone of 1942. In 1942, tip growth had been essentially completed by 

 May 16, only 0.4 cm. having occurred after that date. 



