tg11] BURNS—HURON RIVER VALLEY 117 
those plants which habitually grow at levels of peat bogs, where the surface 
strata can dry out, must have xerophytic adaptations if the climate is such 
that drying out of these levels may occur.” 
In addition to the variation in water level due to wet and dry 
periods, there is the variation from month to month during each 
year. This difference is shown in fig. 7, which gives the results 
obtained April 20-August 3, 1905, in the zones at First Sister Lake. 
The data were gathered for the most part by STEELE. Holes were 
MAY SUNE SULLY AGG. 
20 = ea et eos 27 2 z S28 Os 2a oe 
20 2, 
TE 
/O “Sa /O 
Yo) ay : a 2 oO 
sot Se td i! Ss /O 
ba Ste \’-+ > fen he aL. 20 
i AE at Se 
30} fat ah ~ 30 
a CRE nae 
ZO I 
50} ad Fei 
6 
; ae 
WATEA TABLE 
Fic. 7.—The results of measurements taken to determine the variations in 
water table in the different zones at First Sister Lake; variations are given in 
dug in the peat of the different zones to a considerable depth, and 
a stick placed in a horizontal position at the top. From this 
stick measurements were taken daily to the top of the water 
standing in the holes. These were plotted and the result shows 
in the figure just given. 
The bog sedge zone shows practically no variation, although 
there would have been some, especially on the landward side, 
had the measurements been started very early in the spring. 
This however would be too early to affect the vegetation. The 
open water shows some variation in the summer, but the bog 
