116 Canadian Record of Science. 
Thus at the plain we begin with the region of palms and 
bananas; at 1900 feet pass into the region of the tree fern 
and fig; 3800 feet brings us to the region of myrtles and 
laurels; at 5700 feet we encounter the evergreen dicotyle- 
donous trees; at 7600 feet, the region of deciduous trees ; 
9500 feet, the region of spruces; 11,400 feet, the region of 
rhododendrons; 13,500 feet, we enter the region of Alpine 
plants, and at 15,200 feet encounter the snow limit. 
We thus find that there are eight distinct regions, both 
with reference to latitude and altitude, in which corre- 
sponding forms of plant life occur, whence it appears that 
both increasing elevation and increasing latitude, through 
diminishing temperature, exert the same influence upon 
plant life. 
Were the surface of the earth everywhere uniform, and 
no other modifying influence felt, the distribution of plants 
would also be tolerably uniform within the limits thus 
assigned ; but even within the same line of latitude, great 
variations are to be noted both in climate and vegetation. 
Temperature decreases at the rate of 1° for every 200 or 400 
feet of elevation, and were the surface of the earth suffici- 
ently uniform, there would be a regular variation in vege- 
tation and definite limitation of plant life with increase of 
elevation. But on steep mountain slopes, less heat will be 
absorbed and radiated into the surrounding air than upon 
plateaus even at a much greater elevation, whence it fol- 
jows that plants which are confined to a relatively low ele- 
vation in the first case, become abundant at much higher 
altitudes in the second case. This affords an explanation, 
therefore, of the well known occurrence of certain plants at 
unusual elevations. 
This fact finds a familiar illustration in the progress of 
vegetation on the slopes of mountains, where the same spe- 
cies extend from the plain, for some distance up the slope. 
As spring approaches, the plants on the plain will be found 
to come into bloom first, but as the season advances, the 
same species will come into bloom at successively later 
periods of one or more days, corresponding to difference in 
elevation. 
