VOL. XX. (i) 
FLOWERING OF PLANTS 
*3 
The most striking instance of the effect of the temperature 
is the behaviour of arctic plants. 1 In Nova Zembla the summer 
consists of two months, July and August, during which the 
mean temperature is about 5 0 C. In these conditions, cases 
such as the following occur : at Pitlekaj the last nine days of 
June showed a mean temperature of below o° C., while the 
average for the first nine days of July was between +4° and 
+6°, and on July 10th all the four species of Willow were in 
full bloom, the dwarf Birch, Sedum -palustre, Polygonum, 
Cassiope, and Diapensia were in flower, and within a week the 
whole vegetation was flowering. There was, in fact, a great 
rush or explosion of all sorts of flowers as soon as the tempera- 
ture rose : not that dropping fire which begins with us with 
Mezereon in January and ends with Ivy in the autumn. 
In the Arctic Regions temperature seems the absolute 
master, but in our climate this is clearly not so. The best 
evidence of an inherent tendency to flower on a certain date is 
that given by Askenasy 2 in his observations on Primus avium 
(the Gean or wild Cherry). He recorded the weight of 100 buds 
at regular intervals throughout the year, and thus got the 
following results : — 
grams. grams. 
July 1st 
1 1 
November 1st 4 | 
August 1st . 
• 2 1 
Period I. 
December 1st 4 - Period II. 
September 1st 3 1 
January 1st 4 ) 
October 1st 
4 J 
grams. 
February 1st . . 
March 1st 
6 i Period III. 
April 2nd 
23 j 
April 8th 
43 j 
There are 
thus three periods : I., Formation ; II., Rest ; 
IIP, Development. So much for preliminaries ; the really 
interesting point is the reaction of the buds to forcing by 
1 Kjellman, in Nordenskiold’s Six* dun und Forschungen , 1885, pp. 449, 467. 
2 Botan : Zeitung, 1877. 
