2IO 



BOTANICAL GAZETTE 



[march 



the opening of the buds and the formation of new leaves. With 

 this point in view, measurements were made on a young white 

 pine stand of natural origin on May 3, 1913. The trees varied 

 in age from 4 to 1 1 years and were in a thrifty, vigorous condition. 

 On this date the buds were found to have opened and the young 

 stems to have elongated 0.5-2 . 5 inches. All the growth in length 

 had occurred in the preceding 10 days. Neighboring trees which 

 were older showed less pronounced elongation of young parts; 

 but growth had been in evidence in older, less favored trees since 

 March 29, 1913, and cell division at least since April 20 of the same 

 year. It follows, therefore, that growth in thickness begins before 

 growth in length, and apparently, at the start at least, at the cost 

 of reserve food material. No correlation exists between the two 

 in white pine. 



Concerning the time of cambial awakening, the researches 

 of others bear out the conclusions of this paper. Some of Chris- 

 tison's (5) are given in table E. It should be noted, however, that 

 Christison's results were obtained from bark measurements and 

 do not necessarily indicate xylem formation. 



TABLE E 

 Growth awakening in coniferous species, Edinburgh, Scotland 



MiscHKE (24) also made observations on this point, but did 

 not include white pine among the species investigated. Wieler 

 (39), however, examined three white pines in his experiments of 

 1894. Two of these were from a closed 40 year old stand, the third 

 a 15 year old tree from another stand, all near Dresden, Germany. 

 Growth was in evidence in the younger specimen to the extent of 

 13 or 14 tracheids on April 24. No growth occurred at the base of 



