2()2 GLAUCUS ; OR, 
admit the air. You must guard against this by 
occasional stirring of the surface, or, as I have 
already said, by syringing and by keeping on a 
cover. A piece of muslin tied over will do: but a 
better defence is a plate of glass, raised on wire 
some half-inch above the edge, so as to admit the 
air. I am not sure that a sheet of brown paper 
laid over the vase is not the best of all, because 
that, by its shade, also guards against the next 
evil, which is heat. Against that you must guard 
by putting a curtain of muslin or oiled paper 
between the vase and the sun, if it be very fierce, 
or simply (for simple expedients are best) by laying 
a handkerchief over it till the heat is past. But if 
you leave your vase in a sunny window long enough 
to let the water get tepid, all is over with your pets. 
Half an hou1’s boiling may frustrate the care of 
weeks. And yet, on the other hand, light you must 
have, and you can hardly have too much. Some 
animals certainly prefer shade, and hide in the 
darkest crannies; and for them, if your aquarium 
is large enough, you must provide shade, by arrang- 
