oka? BOTANICAL GAZETTE [AUGUST 
to lower. The readings given in line D were taken 18 inches 
(45.8 cm.) below the surface, and were continued for only a short. 
time; the temperature was surprisingly low. 
The next figure (fig. 5) was furnished by Mr. HAROLD STEELE, 
and gives the results of short readings in several zones. These 
readings were made in 1904 at the same lake. The soil readings 
LUEY 
Se, See Fe” | AS GR GR +” Tele" ¢ MP a 
30 \ N\_A 
STAI A 
‘ Wes VV 
oO 
SHRUB BOG-SEOGE. 
a Ss ap a AUGOS FT: 
24 25 2 7-2 30 3 / ae | 
20 NA at f 
ps eh A, ! V/ u 
Oo 
TAMARACK POPLAR 
Fic. 5—Temperature reading taken in different zones at First Sister Lake by 
STEELE, in summer of 1904; explanation in text. 
are taken 18 inches (45.8 cm.) below the surface. This shows 
that the soil under the tamaracks is the coldest. The same is 
reported by TrANsEAU (18). As the writer had only one set of 
thermographs at his command, the readings could not be made 
simultaneously, but the data gathered seem to show that this 
made little difference in this case, as the temperatures were sta- 
tionary. The soil temperatures were: tamarack, 6 C.; bog 
shrub, 7°5 C.; poplar, 7°5 C.; and bog shrub, 10° C. These 
