18 THE BUTTERFLY VIVAKIUM. 



then be added, taking care to select those which will 

 thrive best in such a situation, but not omitting a 

 few of the more hardy and ornamental Terns . In the 

 earth, certain tin or zinc tubes are supposed to have 

 been sunk, for the purpose of receiving and conceal- 

 ing small bottles of water, in which the stalks of 

 different kinds of plants required for the food of the 

 Caterpillars may be plunged, in order to keep them 

 fresh. This contrivance is very necessary, inasmuch 

 as the foliage often required for the Caterpillars may 

 be of a kind that could not be made to grow within 

 the case— that of the Oak or Elm, for example. We 

 may suppose, by way of illustration, that the col- 

 lector has been so fortunate in his rambles in the 

 woods as to capture a larva of the splendid Purple 

 Emperor, which generally feeds on the Oak. It is 

 evident that, in such a case, it would be necessary 

 to keep a sprig of Oak continually fresh and green 

 in the Vivarium — for which purpose one of the con- 

 cealed bottles of water would be found precisely the 

 expedient required. 



Pots, with small plants in flower, may be 

 plunged to their rims in other parts of the earth of 

 the Vivarium which have been arranged for that 

 purpose — an addition which will not only add 

 beauty and variety to the general aspect of the 



