142 THE WATER CABINET. 
cost of its life. I have several times introduced the 
Hydrachna into my jars of Nepa, but have never yet 
witnessed the parasitic deposit of the eggs. In confine- 
ment, the Nepa is the least hardy of any creature in the 
collection, if the sun strikes the jar it perishes, and it 
will not live long unless it has means of occasionally 
leaving the water—hence a broad jar should be used for 
it, and a small piece of pumice stone should be floated in 
it, to form an island on which the insects may take 
refuge. 
