SMITHSONIAN MISCELLANEOUS COLLECTIONS 

 VOLUME 140, NUMBER 1 



CLASSIFICATION AND MULTIPLICITY 



OF GROWTH LAYERS IN THE 



BRANCHES OF TREES 



AT THE EXTREME LOWER FOREST BORDER 

 (With 36 Plates) 



By 



WALDO S. CLOCK 



Macalester College, Saint Paul, Minn. 



R. A. STUDHALTER 



Texas Technological College, Lubbock, Tex. 

 AND 



SHARLENE R. ACERTER 



Macalester College, Saint Paul, Minn. 



(Publication 4421) 



CITY OF WASHINGTON 



PUBLISHED BY THE SMITHSONIAN INSTITUTION 



JUNE 17, 1960 



