NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. 22/ 



By selecting the proper radius, one could count 12 sharp contacts 

 involving six years of growth. 



TTAp i-4-a {1938-1939) 

 2 see + 2 dee + i s arc— 3 tfs— 2 years. (See table 52, p. 134.) 



The increment for 1938 shows i see and 2 dee for 2 tfs, whereas 

 that for 1939 shows i see for i tf. 



TTAp 2-i-a (193S-1939) 

 4 see — 2 tfs — 2 years. 



In 1939 TTAp 2 grew an extra see, probably because of irrigation 

 in July. 



TTAp 2-3-a (193S-1939) 

 2 see + 2 psee + i sL + 2 dL + i d ^L— 4 tfs— 2 years. (See table 8, 

 p. 102.) 



TTC i-ii-a (1936- 1945) 

 10 see + 1 dee + 10 sL + 10 psL + 3dL + id2L + 3s ares + i d arc — 

 10 years. (See table 54, p. 136.) 



Along different radii of TTC i-ii-a there are 30 sharp contacts, 

 contacts in no way distinguishable from each other. Large amounts of 

 branch material and many sections reveal in many cases those growth 

 layers whose contacts break down to diffuse. However, multiplicity 

 at the lower forest-border region, as represented at Lubbock, Tex., 

 has a degree of incidence and variation as well as a variety of contacts, 

 annual and intra -annual, that makes the dating of growth layers im- 

 possible in the absence of absolute methods. No method of counting, 

 close inspection of contact, or "allowance" for supernumeraries could 

 provide a substitute. 



In TTC i-ii, the increment for 1939 has seven growth layers of 

 which six are sharp or partially sharp; the increment for 1940 has 

 six growth layers of which four are sharp or partially so ; and the 

 increment for 1941 has five growth layers of which four are sharp or 

 partially so. 



TTC 2-3-a (1935-1939) 

 8 see -|- 4 sL — 5 years. 



The increment for the year 1937 has 3 see and i sL which have been 

 reduced to 2 see, 27 cm. outzvard on the branch. The year 1939 has 2 

 see and 2 sL which become 3 see and i sL outward. 



