DICOTYLEDONEJE. 81 



are mostly hemispherical bodies studded with mammae > 

 and thickly beset, as are most of the other genera, 

 with rigid spines. 



Ficoidece and Crassulacea are kindred orders' 

 though perfectly distinct in a botanical point of view. 

 The leaf-like appendages of the latter, and some of 

 the former order, as well as Opuntidcece, cannot be 

 considered simple leaves, because they contain all 

 the principles of the entire plant. Any one of those 

 members separated from the parent and placed in 

 favourable circumstances, readily ejects roots and 

 becomes a perfect plant. Bryophyllum produces vivi- 

 parous progeny from the crenature of the leaves. 

 In short, many of these succulent plants, composed 

 of thick masses of vegetable matter interspersed 

 with membranous fibres and sap vessels, can only be 

 considered as consisting wholly of stem ; and this 

 plenished in every part with the reproductive organs 

 of vegetable life. 



Passiflorece and Curcubitacece are conspicuous 

 orders ; the first for the grandeur of their flowers, 

 the second for the usefulness of their fruit ; both 

 furnishing fine objects of study to the physiologist, 

 whether he regards the causes of the variety of form 

 and colours of the one, or the manner of the enlarge- 

 ment of the enormous fruit of some species of the 

 other. Melons, cucumbers, gourds, &c., are well 

 known exotic fruit -bearing herbs, formed for climbing, 

 though generally trained on the surface of the ground. 

 They are pruned and managed in the manner of fruit 



