88 CHRISTISON—OBSERVATIONS ON 
of an inch above that of April, the first month of the season, and 
only a fourth that of August. The range is greatly less than in 
April, but much greater than in May. The number of records 
of no increase amounted to nearly one-half of the whole, and was 
not much less than in April. 
SPECIES WITH THE LARGEST PROPORTIONAL INCREASE IN SEPTEMBER. 
1992, | 1893, | 1894, | 1895. | Total,| Aver] 5 e 
age | =o 
NM 
Salix sp., — eu oc pe”), 15 25 10-530 *32 | 10°7 
Robinia Pseudacacia, sn ve [oe | TO | 1) 00 Re ee 
Fagus sylvatica, a es 23 fe 10 5 15 30 07 6°9 
Betula alba, _... ie ee nee 5 10 5 15 "BD “09 54 
SPECIES WITH THE SMALLEST PROPORTIONAL INCREASE. 
Quercus robur,.., 
5 rubra,... 
Fraxinus excelsior, Se a a ea 
Populus fastigiata, .., ne ae 5 ss ea fis 5 cl? te ies SU 
Pyrus Aucuparia, a: ee rt ee Ss 5 a 5 ‘01 15 
Salix alone reaches half an inch, and that only once, but with 
the phenomenal score of ‘70. Rodznza follows with -30, which is 
perhaps still more remarkable, as its total annual increase is 
only about a third of that of Sa/zx. No other species scored 
higher than ‘15. 
B. For THE MONTHS IN GROUPS. 
1. Two pertods of three months each—As stated in my pre- 
vious paper, the division of the growing season into two periods 
of three months each, although the only practicable one with 
observations at monthly intervals, does not imply that the periods 
of actual growth are equal in the two divisions. Unquestionably 
there is a great variety both in the normal beginning and normal 
ending of seasonal girth-increase in the different species, but 
