Ww 
N= 
n- 
ns 
of 
ot 
Ww 
le 

INTRODUCTION, 17 
And the pure sweetness of the jessamine ; 
What is it those sighs confess ? 
But we are extending this part beyond our 
limits. Flowers afford a certain means of de- 
termining the state of the atmosphere. ‘“ Many 
species are admirable barometers. Most of the 
bulbous rooted flowers contract, or close their 
petals entirely, on the approach of rain. The 
African marigold indicates rain, if the corolla 
is closed after seven or eight in the morning. 
The common bindweed closes its flowers on the 
approach of rain; but the anagallis arvensis, or 
scarlet pimpernel,” which we often call shep- 
herd’s weather-glass, “is the most sure in its 
indications, as the petals constantly close on 
the least humidity of atmosphere. Barley is 
also singularly affected by the moisture or the 
dryness of the air. The awns are furnished 
with stiff points, all turning towards one end; 
which extend when moist, and shorten when 
dry. The points, too, prevent their receding, 
so that they are drawn up or forward; as 
moisture is returned, they advance, and so on; 
(a; 





