136 BOTANICAL GAZETTE [AUGUST 
strata a few degrees in the early spring. The wave of temperature 
increase falls here slightly behind in March, but the upper strata 
are not prevented from rising in the meanwhile rapidly above the 
freezing point. Though of ecological importance as a protective 
cover during the winter months, and of significance as a bad con- 
ductor of heat and in decreasing fluctuations in temperature, the 
ice and snow do not, therefore, retard appreciably the beginning 
of favorable growth conditions. The maples and willows of the 
TABLE VI 
MINIMUM AND MAXIMUM TEMPERATURES IN THE CENTRAL ZONE AT CRANBERRY 
ISLAND, 1907 to 1910 
Jan. | Feb. | Mar. | Apr. | May| June! July | Aug.| Sept. | Oct. | Nov. |@Dec.J 
Air: 
May. 5 a | Oe 4 25 27.2137 .6133.3135. 135 3° | 23-3 
Leer 19.4|/—24.5|—8.8)—7.7| 0.5} 3.3] 8.3] 7.2/1 6\—5.5|—9.4|—21.6 
Range 37-7| 39-5| 33-8| 34.9|31.1|30.0\26.7|27.8| 36.1! 35.5] 32.7) “40-6 
1 ft.(0.3 m.) 
AX... <2 acta lee ley. ioe. gl 2g | 27-7| 33 9 
MS ° rato G-Glio 78. |t7 ar. G4 f2.5; 8 2.5 
Range .. ach atl 6 6.715 ro | 4.5 5 6.5 
oil: 
5 ft.(1.5 m.) 
EAR oa. cea) 6 ol Of 42.2112. 5117 [23 (26 | 22.5], 22 15-5 
Min... 7.5) 3.0] 4 7.2| 9.5|14 |16 |22 | 20 | 18 | 16.5) 1 
Range. Bo Gost S 5 woo a5 4 5) 4S 
GREATEST RANGE 
Air: max. 35; min. —24.5; range 59.5. 
Soil 1 ft. (0.3 m.): max. 27; min. 0; range 27. 
Soil 5 ft. (r.5 m.): max. 26; min. 3.9; range 22.1. 
bog island are in flower about 8 to 10 days later than those on the 
campus of the university. A persistence, however, in the peat 
substratum of the winter cold and ice through the summer months 
is not proved, at least in this region. The records taken at a depth 
of 5 feet (1.5 m.) below the surface vegetation show a variation in 
temperature between 3°9 C. and 26° C., ie., an annual range 
within 22° C. At this depth only the anaerobic bacterial bog 
flora is most active. The roots and rhizomes of bog plants do not 
penetrate beyond the depth of 2 feet (0.6 m.), and the roots of 
