PLANTS SUITABLE FOR VIVARIA. 39 
the tank there should be a pipe and plug so that water may be 
occasionally drawn off and replaced with fresh. 
It goes without saying that a Vivarium is the more interest- 
ing when plants and animals are living and thriving together. 
As a rule, this can be generally managed. Not only should the 
plants be chosen for the animals, but also for the cases. Plants 
generally do best in those Vivaria which have either two or four 
Fic. 27.—WATER CROWFOOT (Ranunculus aquatilis). 
sides made of glass or two or three sides of canvas as well as the 
glass side or sides. Care should be taken that the pot and the 
plant, or tree, which it contains do not take up too much room 
in the Vivarium. Sometimes, it is a good plan to get rid of the 
pot, as it were, by placing the case on short legs, and cutting a 
round hole in the centre of its floor sufficiently large to receive, 
and just hold tightly the pot near its rim. The plant will then 
have all the advantage of the pot and the Vivarium none of its 
