Plate 29 



XSC ii-i-a. Branch section of Ciiprcssiis arizotiica, cut August 20, 1941. Xylem 



of 1937- 194 1. Variable definition of outer contact of annual increment ; dw of 



"outer thin" gl sharp to nearly nonexistent; multiplicity; typical 1938 natural 



frost effects. 



1937: Diffuse bands of dw ; dL ; see. 



1938: Effects of natural frost (see pi. 30, fig. i) ; dee; psL ; see. 



1939: Inner gl. fairly s border, clockwise its dw breaks twice in succession 

 and lifts away in dL's ; "outer thin" gl, its dw changing from thin 

 and sharp to very faint and dift'use. Without typical frosts of 1938, 

 1939, and 1940 (last two present elsewhere on section) to date the 

 gls, the "outer thin" of 1939 could scarcely be identified as annual; 

 if it were, then 1939 annual increment would include 2 gls. 



1940: Thin see. 



1941 : Nearly complete; scattered cells of psg. Artificial freezing outward 

 on branch. 



