1915] BROWN—PINUS STROBUS 227 
words. WIELER (39) has given some data concerning the termina- 
tion of growth from the three white pines which he investigated 
(table J). In tree I the ring was complete on the north and south 
sides at the base on September 8. In tree II it was complete on the 
south side at the same height on August 28, while in tree III it 
was still in progress on September 8. In general his results indicate 
that in the vicinity of Dresden, Germany, growth in white pine 
ceases slightly earlier than at Ithaca, N.Y., a reasonable conclusion, 
since the former is in a higher latitude. The work of BuckHour 
(2), already cited, is of interest in this connection. While his 
measurements were made externally and are therefore subject to 
the same criticisms as those of Tu. Harrie, certain facts are obvious. 
During the four years over which his experiments extended, growth 
was manifest in the white pine during the last 10 days in August 
and in two as late as September 8. His results serve to accentuate 
the fact that white pine has a long growing season, much longer 
than the European larch, with which he also worked. 
The growing season of tree I may be used, in spite of variations 
which occur between individuals in that respect, as a general indi- 
cator of white pine growth in the vicinity of Ithaca. As already 
indicated, growth in white pine may be divided into two periods: 
(A) growth without cell division and (B) growth with cell division. 
B of necessity follows A. Considering A and B together, growth 
began in tree I before March 29, 1913, and continued until after 
September 19 of the same year, a period of over 5.5 months; and 
this does not include the late phloem development which without 
doubt continued into October. Cell division began before April 26 
of the year in question, and if growth is considered in the narrow 
sense, the period is shorter by several weeks. If there are any 
grounds for the statement that trees complete their seasonal growth 
in a period of 4 or 5 weeks, white pine is an exception to the rule, 
as here the growing season extends over a period of 4-5 months, 
depending on the interpretation of the term “growth.’ 
Differentiation in the annual ring in aerial parts 
- In working up the foregoing data, no stress has been laid on 
differentiation within one and the same annual ring. As is generally 
