1911] DACHNOWSKI—CRANBERRY ISLAND 127 
siders the bog as a habitat, the various causative and limiting 
factors entering into the plant environment are not so readily 
distinguished. In connection, therefore, with the analysis of the 
life conditions in bogs, associated also with the distribution of 
bog plants, and their conflict with species whose range is more 
southern, certain meteorological phenomena have been added 
below. 
CLIMATIC CONDITIONS 
One of the main objects kept in view during the progress of the 
investigation on the ecology of Buckeye Lake, and one which 
seemed to the writer an indispensable preface to both the field 
and the laboratory study, has been the climate of the region. The 
general statistics were taken from’ Bulletin Q of the U.S. Weather 
Bureau Service (17), and from manuscript to which access was 
had by the courtesy of Section Director Hays of the Columbus 
(Ohio) Weather Bureau. No continuous series of climatological 
records have been made on Cranberry Island. The writer made 
records extending over the period of investigation; these records 
were supplemented by Mr. DickEy, whose readings were taken 
each time the evaporation of the bog habitat was measured. It 
is felt that the comparative climate statistics given below are 
generalized data which do not lend themselves to investigation 
in physiological ecology. Though facing the same set of climatic 
factors, few of the species forming the flora of the bog island con- 
front the same physiological problems, and hence any conclusions 
drawn from mere climatic data, without reference to the varying 
functional responses of the different species of plants, are certainly 
inadequate. However, the study of the meteorological observa- 
tions is suggestive mainly in ascertaining the essential differences 
between the local region and the conditions found in the northern 
center of bog formation, and in estimating the average tempera- 
ture and humidity exposure of the plants. The data given in 
table IV are for Columbus, Ohio; for Ann Arbor, Michigan, where 
bogs and swamp-lands are found more abundantly; and for Mar- 
quette, Michigan, where this type of vegetation reaches a still 
higher development. 
