116 THE ROYAL SOCIETY OF CANADA 
It will be evident from the above figures that the southern part 
of Ontario has a larger number of very warm days than any other 
province. It is noteworthy that such species as blue ash, papaw, 
tulip tree, cucumber tree, black gum, _ sassafras, sycamore, 
chestnut and numerous other species occur here and nowhere else in 
Canada. So far as the element of temperature is concerned this 
region has obviously crop-producing possibilities which are not equalled 
by any other part of the Dominion. 
LIGHT. 
Light is essential for the growth of most of the higher plants. 
Bright sunshine not only raises the temperature of the air, but also 
promotes evaporation of moisture from the soil. Other factors 
remaining the same bright sunshine as compared with diffuse light 
accelerates photosynthesis and transpiration. It also influences 
pollination since on a sunny day more insects will be on the wing. 
The duration of bright sunshine can be readily measured in hours: 
in addition the number of hours of diffuse light should also be recorded. 
In summer the higher slopes of mountains and places in higher lati- 
tudes have a longer period of daylight, and this greater duration of 
daylight even with a lower temperature may produce as great an 
effect on plants as a shorter period of light with a higher temperature 
in places lying nearer the equator. Sunshine records for a number 
of places are given in Table VI and the duration of sunshine, diffuse 
light, and darkness at Edmonton and Toronto are given in Table VII. 
TABLE VI. 
BRIGHT SUNSHINE. 
AVERAGE NUMBER OF HOURS, 1909-12. 




Nov.—Apr. May-Oct. 
VICÉOHA PIS ERUN RUE Re CR A Patte Nea ee 578 15265 
VATCOUVEL ES cis Map UE ee ae te eee ee 564 1195 
KAMLOOPS RME RE EEE PELLE TR 659 1,391 
ÉdMONntOR ESRI RARE RTE EE REC 772 1591 
Indian’ Head: yyw ee ea aki kk 694 1,202 
Witnthipe ge Oia rs emt eee ah a ter Ur eh 781 1,289 
Hailevbury,c.s isnt ee ee oes ee UAL 1,222 
TOLONTOR eee sorte Cra ee ee Ne 693 loi 
Montreal Essen Se et eRe aes 618 15239 
Fredericton net RENTE RTE TETE 806 1,190 
Charlottetown ets se RENE Tr ees 653 1,206 
