NO. I GROWTH LAYERS IN TREE BRANCHES — CLOCK ET AL. I4I 



mittently around the circuit and constitute the only evidence of the 

 place where the intra-annual growth layer exists at 44.5 cm. 



The juniper branch TTJ 2-1 (table 68) was cut off the tree Febru- 

 ary 29, 1940. Multiplicity is a bit more prevalent inward on the 

 branch. In the 1936 increment the lens is concurrent. Compression 

 wood just outside the contacts of the mostly sharp, complete, entire 

 growth layers obscures the contacts for a short arc on the inner sec- 

 tion but not on the outer. In the 1938 increment, on the inner section, 



Table 67.— TTJ i-i 

 80 cm. 61 cm. 44.5 cm. 24 cm. 



1937 I see I see i see 



I dee I psce 



I s arc 



1938 I msce I see i see i see 



I dee 



1939 I see I see 2 see i see 



2 sL 



I dL id arc 



psg psg psg psg 



Table 68.— TTJ 2-1 



Inner Outer 



1936 I see I see 



1 psL 



1937 I msee i see 



2 psee I psee 



I d arc 



1938 I msee i see 



ddw 



1939 I see I see 



I psce 

 I dee 

 psg psg 



the densewood shows a distinct tendency for lensing. It gives rise 

 to an interesting situation on the outer section. The densewood, for 

 an arc of 5°, contains a row of cells whose lumens are slightly larger 

 than those of contiguous cells — such is the appearance under high 

 power. Under low power, the row of cells is so nearly invisible that 

 it would in all probability be disregarded by the average student. In 

 contrast, under low-low power it appears to be a genuine lens, diffi- 

 cult to see clearly, it is true, but amply justifying such an interpreta- 

 tion. 



