Plate 30 



Fig. I. XSC ii-i-c. Branch section of Ciiprcssits ariaonica, 9 cm. outward on 

 branch from plate 29, cut August 20, 1941. Xylem of 1937-1941. Definite gl 

 made by natural frost; weak annual contact of 1939 and "outer thin" gl. 

 1937: see with ddw. 

 1938: Definite gl, an extension around circuit of frost injury; dee; see with 



thin dw. 

 1939 : see with heavy dw which separates into two indefinite bands ; "outer 



thin" gl with dw i cell thick. 

 1940 : see with irregular outer contact. 



1941 : inc ; cambium dead by artificial freezing of May 9, 1941. 

 Fig. 2. A'.S'C ii-2-a. Branch section of Ciiprcssiis arizonica, cut September 11, 

 1941. Xylem of 1937-1941. Contrast of weak "outer thin" gl of 1939 and 

 strong outer gl of 1940; contrast in 1939 of strong intra-annual dw and weak 

 annual dw ; different sequences on different radii ; psg. 

 1937: Psce. 

 1938 : Natural frost effects with parenchyma and dw cells ; bands of diffuse 



dw ; dL; see. 

 1939 : Frost spots ; bands of diffuse dw ; see with fairly heavy dw which 



separates into two indefinite bands ; "outer thin" gl with thin, weak, 



intermittent dw. Actually, both see's are diffuse over a portion of 



their contacts. 

 1940: msce ; see; sL. 

 1941 : see; psg; cambium probably dead, as an effect of artificial freezing 



outward on branch May 9. 



