358 BOTANICAL GAZETTE [NOVEMBER 
Consequently, low shrubs, and herbs which pass the winter by means 
of underground stems, are well protected from low temperatures and 
sudden temperature changes. The ice further results in lowering the 
temperature in spring and in retarding the beginning of favorable 
growth conditions. 
The percentage of sunshine is not published by the several sta- 
tions, but the number of clear and partly cloudy days is stated. The 
numbers from the various stations show marked differences, due to 
different standards established by the observers; but perhaps these 
are largely eliminated in the average. If we take the average num- 
ber of clear days, add to it one-half the number of partly cloudy days, 
and divide by the number of days in a year, we obtain a percentage 
of forty-six. This probably approximates the percentage of sunshine. 
In comparison with the rainfall data for Halifax and St. John, it 
is notable that in the latter localities the mean rainfall, both monthly 
and annual, is considerably larger. The annual precipitation 
exceeds that of the Huron valley by fully 20 inches (50%), oF about 
40 per cent. Finally, the sunshine percentage is slightly lower, being 
39 for Halifax and 42 for St. John. 
Temperature.—The following table exhibits the monthly and 
annual means for the several stations already cited: 
MEAN TEMPERATURE IN °F. 
Ann. 
Jan. | Feb. | Mar.|April | May | June | July | Aug. Sept.| Oct. LT 
Ann Arbor. ..03-..; 22.2) 23.1| 30.6] 45.4| 53-2| 67.3| 72-0] 69.3] 62.5) 49-9 36-4 os r. 
SPE os eee 25.9 roe ie po es 33 63.5| 71-1] 69.7] 6-8) 49-9 ee! a5 a3 
POGeNON sc, 26.1] 20.3| 32.7| 47.5| 59.4] 60.4 74.8] 71-8 64.8 54-3 ay 26.7| 47-4 
PRN ys. 24.7| 21.7} 31.3] 50.2) 56.5] 68.4] 71-8) 67.6] 63.0} 49- a 27-1| 46.0 
Le ee eae 22.6| 21.4) 27.6] 45.3| 56.0] 66.9] 70.0| 68.1| 62.2) 49-5 ° = 27.0| 47-1 
Pay | a a 23.1| 22.8| 30.4| 40.5] 57-3| 60.1| 72-2| 68.4 6.5 
Pee : .0| 47° 
DISSE. 24.1| 22.2} 30.8] 46.9] 56.7} 67.1] 71-9} 69-1 62.6 v4 
— ome merar Se .1| 4: 
St. John, N. B....... 18.6] 18.71 26.3| 38.6| 48.8| 56.3| 6x.o| 6r.3] 55-6] 44-7] 30-0) O70) g3.2 
Hantex, N.S..... 2. 22.0| 22.7| 28.7| 38.2] 48.7| 57-6] 64.2) 64.8 58.2| 48.0] 38-2 27 ee 
: is mpara- 
The table shows that the temperature conditions are a na 
tively uniform throughout the basin. The maximum eee dats 
: eae e 
peratures occur in July and August. But the significance © . 
< ion 1 nce , 
becomes more apparent, in so far as the bog vegetation sie ). 
when they are compared with those of St. John a 
. une, 
It is to be noted that, although the average temperature for J 
