I14 BOTANICAL GAZETTE [AUGUST 
This was after the most active vegetative period. Conditions 
in the bog shrub zone closely resemble those just described. In 
bog sedge the records show less regularity and resemble more 
closely swamp conditions, especially, as has been said before, in 
bogs where this zone is narrow. 
In the two outer zones, the temperatures recorded resemble 
more closely the upland and drained swamp conditions. Here 
they ranged about 18° C., in July reaching this mark early in the 
summer. They would have a less detrimental effect upon the root 
systems of the plants in these zones. 
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Arbor, Mich; August 23-30, 1907; the instruments were in the bog sedge zone; 
the bulb of the soil thermograph was 20.4 cm. below the surface; the upper line 
shows record of the air, the lower the soil Deneck 
Fig. 5 also shows the range of air temperatures for the periods 
given above. The results are similar to those already given by 
the author. 
The record of the soil and air thermographs for one week, 
August 23 to August 30, is reproduced in fig. 6. This is only one 
of numerous records which were taken, and shows the very slight 
variations in the temperature of the soil and the great variations 
in the temperature of the air. The greatest variation in soil 
was about 1° C.; that of the air was 17° C. In fig. 3, the varia- 
tion in air temperature was 25°5 C. 
