40 THE VIVARIUM. 
disadvantages. Of course the rest of the bottom of case must be 
covered with mould, sand, gravel, or moss, according to the 
animals which the case is to contain. 
In summer, a Vivarium like Fig. 12 may have the boiler with- 
drawn, and the space which it occupied filled with suitable mould 
Fic. 28.—BROOKLIME (Veronica beccabunga). 
in which certain plants may be grown. A small ordinary flower- 
pot can be made both ornamental and useful in a Vivarium by 
tastefully covering its sides, by the help of Portland cement, 
with small pieces of coke, and then dipping the whole in liquid 
cement of the consistency of cream. The pot will then hold the 
