1915] BROW N—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 1913. 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 9g 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 110 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 nies 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 
