NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. 239 



Branch TTP 21-2 was cut off July 17, 1940, by which time it had 

 grown I see + 1 dgl. The diffuse growth layer, which is interior to the 

 see, shows scattered radial columns of cells whose outer members re- 

 main narrow as in typical densewood. In 1937, 3 see are present. 



TTP 2i-s-a (1936-1940) 

 7 see + I sL — 5 tfs — 5 years. 



The increments for 1936 and 1937 each contain 2 see. 



TTP 2i-6-a {1935-1940) 

 7 see -|- I dee — 6 tfs — 6 years. 



The dee represents 1938. Both 1936 and 1937 have 2 see each. 



TTP 2i-8-a (1936-1940) 

 5 see + I msec + i psee + i d arc — 5 tfs— 5 years. (See table 86, p. 151.) 



The I msce represents 1938, and the i psce represents 1939. Both 

 of these become sharp 26 em. outward on the branch. Again 1936 and 

 1937 are represented by 2 see each. 



TTP 2i-io-a (1936- 1940) 

 5 see + 2 dee — 7 tfs — 5 years. 



The 2 dee represent 1939 and 1940. Both 1936 and 1937 have 2 see 

 each. Therefore seven diameter flushes correspond to seven tip flushes 

 put down in five years. 



TTP 22-2-a (1940-1941) 

 2 see + I psee + i dee — 2 tfs — 2 years. 



Here, the intra-annual growth layers, i psce and i dee, do not cor- 

 respond to tip flushes. 



TTP 24-3-a (1935-1941) 

 5 see + 3 msce + 2 dee + i jkL— 7 years. (See table 92, p. 156.) 



The growth layers designated 3 msce represent 1939, 1940, and 

 1941 ; I dee represents 1938. In the 1941 increment, the lightwood of 

 the msce is lenticular, the densewood being continuous around the cir- 

 cuit. When high power was used on what had been interpreted as a 

 lens, it was revealed that the lightwood only, and not the densewood, 

 is lenticular. Thus the question again arises : "Does a lens ever rep- 

 resent an annual increment ?" This naturally creates the further ques- 



