242 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



linear" tip flushes also contains a growth layer for each. There is very 

 little difference among the outer boundaries of the increments for 

 1943, 1944, and 1945, whether annual or intra-annual. The chief dif- 

 ference lies in vessel size and number, and this difference is only of 

 local use. 



Branch XSC i-i (table 42, p. no) was cut off May 10, 1940, after 

 having been frozen April 8, 1940, at 81 cm. A summary of sections 

 a at 81 cm. follows. 



13 see + I msce + 2 psce + 2 sL + 5 psL + i dL -f i s iL + 2 iL + i ddw 

 + inc — 8* years. 



XSC 1-2 (1932-1940) 



a. 13 see + 2 msec 4- i Psce -J- 7 sL + 2 msL -f- 2 psL + dL's 4- 3 s ^L + 

 2 d iL -}- I d arc + I ddw + inc L— 8* years. (See table 102, p. 162.) 



b. 17 see + I psce + 10 sL + i msL + 3 psL + 2dL + 2siL-|-5d2L + 



I d arc + I s ddw + 3 ddw + inc — 8"^ years. 



Branch XSC 1-2 was cut off May 10, 1940. Both XSC i-i and 1-2 

 were frozen artificially on April 8, 1940, the latter more than twice as 

 long. The effect of freezing in XSC 1-2 was much more severe, the 

 initiation of recovery apparently delayed, and the amount of recovery 

 much less in the time between freezing and cutting off the branch. At 

 the time of freezing of XSC 1-2, only scattered lenses of one or two 

 rows of cells had been formed, and by the time of cutting, one to six 

 rows of recovery cells had been added. 



XSC 1-3-a (1936-1939) 

 8 see + 7 sL — 4 years. 



The cambium had not yet become active by April 9, 1940, when 

 branch XSC 1-3 was cut off. If we include the years 1930 to 1935, 

 which do not appear in the summary above, we obtain : 



18 see 4- 2 msce -\- 11 sL -f i dL — 10 years. 



The multiplicity in sections b is without doubt even greater. In fact, 

 on one radius, there are 27 sharp growth layers for nine years. Other 

 radii give other combinations, not duplicating the first radius. 



XSC 1-4-a (1933-1940) 

 9 see + I msce + 10 sL + i msL + 3 dL + 2 ddw + inc — 7* years. 



If the 3 years prior to 1933 are included, we must add 7 see, i 

 psce, and i dee. Therefore, the years 1933-1939 include 19 sharp 

 growth layers, representing 7 years, and the interval 1930-1939 in- 

 cludes 26 sharp growth layers for 10 years. 



