42 FIRST FORMS OF VEGETATION. 
months, their vitality is unimpaired ; and though 
subjected to the scorching rays of the summer's 
sun, they continue green and unblighted. Even 
when thoroughly desiccated into a brown un- 
shapen mass that almost crumbles into dust when 
touched by the hand, they revive under the in- 
fluence of the genial shower, become green as an 
emerald; every pellucid leaf serving as a tiny 
mirror on which to catch the stray sunbeams. 
Specimens dried and pressed in the herbarium for 
half a century, have been resuscitated on the ap- 
plication of moisture, and the seed procured from 
their capsules has readily germinated. They grow 
freely in the Arctic regions, where there is a long 
twilight of six months’ duration ; and they luxu- 
riate in the dazzling uninterrupted light of the 
tropics. They are found thriving amid moist 
steam-like vapours, with orchids and tillandsias, 
in the deep American forests ; and they may be 
seen in tufts here and there on the dry and arid 
sands of the Arabian deserts. It matters not to 
the healthy exercise of their functions whether the 
surrounding air be stagnant or in motion, for we 
find them on the mountain top amid howling 
winds and driving storms, and in the calm, silent, 
secluded wood, where hardly a breeze penetrates 
to ruffle their leaves. 
The range of flowering plants is circumscribed 
