8o 



SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



Fig. 22. — XSC 1-3-b. Increments for 1938-1939. Lensing; multiplicity in cambial 

 and growth activities, and in gls. Interpretation shown in figure 23. 1938: sL; d ^L; 

 see ; psL and sL, compound ; 1939 : spot of natural frost connected with an arc ; see ; 

 compound sL. 



XSC l-3-b 



Fig. 23. — An interpretation of figure 22. Localized and periodic activity of growth 

 processes. Contacts sharp, diffuse, or invisible. Gls are numbered i to 9 to correspond 

 to periods of growth activity. If the contact between 6 and 7 is interpreted as invisible 

 at both extremities (blank spaces), then both 6 and 7 become entire gls. 



