THE BOTANIC GARDEN. l65 



We must now trace and retrace all the paths 

 which divide the beds, advancing from left to 

 right, to the bottom of the garden. The plants 

 are in double rows in the families which con- 

 tain few trees ; and in those which require more 

 room, and pass the winter in the air, as the 

 acercey the rosacea?, the amentacece and the coni- 

 ferce, they occupy the middle of the bed. Wicker 

 cages open on one side are placed over those 

 which it is necessary to defend from the north 

 wind or from the sun, and bell-glasses over those 

 of the torrid zone which require a concentrated 

 heat. The aquatic plants, as the naiades, the 

 njmphece, water-lilies, and some species of ra- 

 nunculus, are kept in tubs of water ; and those 

 which thrive best in rocky ground, as several 

 species of fern and houseleek, sempervivum, are 

 provided with an artificial soil. To the palms, 

 of which we have only twelve or fifteen species, 

 succeed the juncece, the liliacece where are found 

 the aloes ; the iridece, the orchideas, and the hodro- 

 charidece among which is the valisnerea, an 

 aquatic plant remarkable for the manner of its 

 fecundation ( i ). Here terminates the series of 

 monocotyledon plants, of which there are eleven 



(i) A plant deep-hid in Rhone's impetuous tide 

 Ten lonely months beholds his waters glide ; 

 Th' eleventh, when genial love renews the year, 

 The females rising o'er the stream appear, 



