NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. I97 



offset twigs. Each shows i see. On unstained sections, under the 

 wide-field binocular, sections a show i see plus a 45° lens. 



WPe 1-2, cut off January 21, 1945, had one twig as an offset second 

 flush. Sections a from the first flush contain i see plus i dee ; in con- 

 trast, the wide-field binocular shows only one growth layer. Sections 

 b and c from the offset flush contain i see only. 



Although no sections were taken from WPe 1-3, it is of interest 

 because it recorded the effects of a cold spell. An offset flush began 

 May 27, 1945, after the tip of the first flush had died. By June 3, the 

 first offset twig had died and the second had begun to grow, a situa- 

 tion which had become rather general on the tree by June 10. Those 

 branches with continuous growth, as well as those which had set ter- 

 minal buds by June 10, possessed a zone halfway out on 1945 tip 

 growth where the leaves were closely bunched. One of these even 

 showed terminal bud scale sears. This slowdown of tip growth oc- 

 curred between April 29 and May 6, a cold interval with heavy frost. 

 Our records say "little or no tip growth" for the 7-day interval. 



WPe 1-4, cut off January 21, 1945, contained two sets of terminal 

 bud scale scars in its 1944 tip growth and hence three in-line tip 

 flushes. The first was 12.5 cm. long, the second 14 em., and the third 

 1 1.5 cm. Sections a, immediately inward from the end of 1943, eon- 

 tain I see for 1943 and i see plus i psee for 1944 — all these for four 

 tip flushes for two years. Sections b, part way out in first 1944, show 

 I see plus I psee for three tip flushes for one year. Sections c, from 

 second 1944, contain i see plus i psee for two tip flushes for part of 

 one year. Sections d, from third 1944, contain i see for i tip flush 

 for part of a year. Hence, the first two tip flushes of 1944 correspond 

 to one diameter flush, and the third tip flush corresponds to the second 

 diameter flush. 



WPe 1-5 came out as a secondary branch from one whose outer part 

 constituted WPe i-i. WPe 1-5, cut off June 17, 1945, contained a 

 first flush of 1944, II cm. long, a second offset flush of 20 em., and 

 1945 as an in-line continuation of second 1944, 6.5 cm. long and dead 

 at the tip. Sections a, from first 1944, show i see plus i psee for 

 1944, and I inc for 1945, corresponding to three ( ?) tip flushes for 

 more than one year. Sections b, from the second, or offset, flush of 

 1944, show I see for 1944 and i inc for 1945, corresponding to two 

 ( ?) tip flushes for parts of two years. 



WPe 1-6, cut June 17, 1945, contained at least two in-line tip 

 flushes for 1943, two tip flushes (the second offset) for 1944, and one 

 uncompleted flush for 1945. The outer tip flush of 1943 measured i 

 em.; the first flush of 1944 measured 21 cm., the second 24.5 cm.; 



