iQiSl BROWN—PINUS STROBUS 221 



period of 4 years. The results were plotted in curves where the 

 abscissas represented 5 day periods and the ordinates increase 

 in circumference in sixteenths of an inch. In each of the four 

 curves for white pine, from several to many growth fluctuations are 

 evident. Still other researches could be cited to emphasize the 

 same point. Many irregularities in growth occur during the season 

 of cambial activity. 



Comparative growth studies between different individuals of 

 white pine (not in the same stand) were also carried on during the 

 summer of 19 13. In such investigations only temporary mounts 

 were made and the necessary data secured from these. A few 

 extracts from this part of the work follow. 



On May 10 two cuttings were made at the base of the "Wolf" 

 tree previously described, one on the north side and one on the 

 south side. The first exhibited about 10 tracheids (7 complete) as 

 to size on this date, while 12-14 tracheids were in evidence on the 

 south side. On May g two cuttings were secured from a large 

 white pine which presented different conditions of site, although 

 in the same vicinity. This was a mature specimen some no feet 

 high and 22 inches diameter breast height. It stood in a mixed 

 hardwood stand where the land sloped sharply to the south. 

 Ground cover was sparse. The tree, while mature, appeared to be 

 still in vigorous growth. The north cutting (next to the bank) 

 exhibited 2 tracheids, neither complete as to size; while in the 

 south cutting no new tracheids were to be seen. Without doubt 

 growth- was going on vigorously in the upper part of the tree at 

 this date. Observations on the same tree at a later date showed 

 similar discrepancies. On June 13 the south basal cutting of the 

 "Wolf" tree showed 20-25 tracheids already formed; 15 or 16 of 

 these had apparently attained their ultimate size. The same 

 cutting from the older specimen at that date possessed 11-13 new 

 tracheids, 7-9 of which had attained approximately their maximum 

 size. The amount of growth was decidedly less in the older 

 individual. 



Even wider discrepancies may be expected than the above 

 where the differences in age are greater. For example, a young 

 tree was examined on the same date (June 13). This was a thrifty 



