l86 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



tfs 



Insofar as our materials are concerned, the one-to-one correspond- 

 ence, number i, is the most common and number 5, the second. The 

 preponderance of unity or of multiplicity depends to a certain extent, 

 apparently, upon the rainfall, and hence the soil-moisture regime 

 under which the respective trees grew. 



The problem of growth slozv-dozvnJ — The presence of terminal bud 

 scale scars leaves no doubt that tip growth ceased at least temporarily 

 during a particular growing season. But that they always occur at the 

 end of a year, or that diameter growth ceases with tip growth, is not 

 necessarily true. 



The condition of continuous growth throughout a season gives way 

 gradually to a situation wherein, by successive stages, growth slows 

 down increasingly until the final stage of complete cessation, once or 

 more within the season. In gymnosperms, the problem intermediate 

 between the two extremes resolves itself into a study of sets of so- 

 called bare-needle zones. In angiosperms, it is a study of shortened 

 intervals between leaves or their scars. 



'■ Because of continued repetition of descriptive phrases in this section, they are 

 abbreviated as listed on page 101. 



