200 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



to terminal bud in longitudinal sections are shown by the diagram, 

 text figure 44. 



Since tip flushes are measured from terminal bud scale scars to ter- 

 minal bud scale scars located at the bases of the terminal buds, any 

 xylem within the bud, although formed in one year, will augment that 

 of the following year and in any measurements will be taken as part 

 of it. 



BUD 



Fig. 44. — TTP 20-3-c. Projection of mature xylem into the terminal bud. 

 At the left, both lightwood and densewood extend into the bud ; at the right, 

 only densewood extends into the bud. 



Several branches of TTP 22 illustrate xylem within the bounds of 

 a terminal bud formed at least a year prior to the cutting date. TTP 

 22-1 was cut off on January 17, 1942. Its tip growth had been meas- 

 ured January 4, 1941, and also on the date of cutting. On January 4, 



1941, the length of the terminal bud was 3.2 cm. On January 17, 



1942, measurements gave 4.3 cm. for 1941 tip growth plus 2.5 cm. for 

 the new terminal bud. Sections a came from 1.5 cm. inward from the 

 outer end of 1940 tip flush and contain the following: i see for 1940 

 and I see plus i dee for 1941. The xylem for 1940 constitutes three- 

 fifths of that present in the sections. Sections b came from 0.5 cm. 

 outward in 1941 tip growth and therefore within the longitudinal 



