SEA DESERTS AND LAND DESERTS 1g 
It is in the depths of the ocean, however, that the 
greatest deserts of our globe are to be found. The 
luxuriant Seaweed gardens that decorate the shal- 
lower waters of the sea, especially where a rocky bot- 
tom provides secure foothold, dwindle rapidly as the 
depth increases, owing to the diminution of light, and 
when the coastal fringe is left they cease. In the inky 
darkness of the ocean depths, amid absolute stillness 
and a temperature little above freezing, plant life of 
any sort is unknown. Only the flinty skeletons of 
diatoms and other minute forms of vegetable life 
which inhabit the surface layers, raining slowly down 
throughout the ages, tell that plant life exists in the 
sea at all. 
On land, the larger deserts are found in the coldest 
and in the hottest regions. Around the North and 
South Poles lie great areas where the perennial low- 
ness of temperature and the consequent almost con- 
tinuous covering of snow and ice render plant life 
impossible. But just as the Eskimo live under con- 
ditions which would be wellnigh prohibitive to in- 
habitants of more temperate regions, so many of the 
higher as well as the lower plants creep northward 
far beyond the Arctic Circle, where, awakening from 
a nine months’ winter sleep, they break from the still 
half-frozen ground to brighten the brief summer with 
their leaves and flowers and fruit. The flora of 
Greenland, for instance, which we generally think of 
as an ice-bound and inhospitable land, numbers some 
400 species of Seed Plants. These live mostly on the 
cliffs and steep ground that fringe the coast, where 
they are clear of the great icefields which bury the 
interior of the country, and in many places descend 
