THE WONDERS OF THE SHORE. 263 
ing the bits of stone mto piles and caverns. But 
without light, your sea-weeds will neither thrive nor 
keep the water sweet. With plenty of light you 
will see, to quote Mr. Gosse once more,! “thousands 
of tiny globules forming on every plant, and even 
all over the stones, where the infant vegetation is 
beginning to grow; and these globules presently 
rise In rapid succession to the surface all over the 
vessel, and this process goes on uninterruptedly as 
long as the rays of the sun are uninterrupted. 
“ Now these globules consist of pure oxygen, given 
out by the plants under the stimulus of light; and 
to this oxygen the animals in the tank owe their 
life. The difference between the profusion of 
oxygen-bubbles produced on a sunny day, and the 
paucity of those seen on a dark cloudy day, or ina 
northern aspect, is very marked.” Choose, therefore, 
a south or east window, but draw down the blind, 
or throw a handkerchief over all if the heat become 
fierve. The water should always feel cold to your 
hand, let the temperature outside be what it may. 
ae fy) 
