EXOTIC FLOWERS AND PLANTS. 205 



the general potting time, the bark must be again 

 turned^ to keep up the necessary temperature. 



Hot-house plants are very liable to be preyed 

 on and disfigured by insects, especially the red 

 acarus (not spider, as it is erroneously called), 

 the different species of coccus, as well as the 

 universal plague, the aphis. The dry heat of a 

 stove is peculiarly favourable to these insects, 

 and, unless the house is heated by, and fre- 

 quently saturated with steam, the plants rarely 

 look healthy. But this is not suitable for all; 

 succulent plants, which are natives of hot rocky 

 countries, need but little water, and, conse- 

 quently, require dry air. It is evident, there- 

 fore, that a collection of tropical plants cannot 

 all be cultivated properly in the same house. 



Hot-houses in the conservatory style are by 

 far the most interesting, and may be the most 

 magnificent of our horticultural buildings. Many 

 plants of the torrid zone are nothing while con- 

 fined to a pot or tub, however large. But when 

 planted in prepared ground, and covered with 

 a sufficiently lofty glazed roof, the plants, and 



