STRUCTURAL BOTANY. 23 



moncEciously or dicecioiisly polygamous, and then inquire 

 for the order in Monoacia or Diaecia. 



62. The quality of the fruit enables us to ascertain the 

 Orders of the classes Didynamia (XIV.) and Tetradyna- 

 mia (XV.) 



G3. The Orders of the 24:th class, Oryptogamia, are, 

 Natural Orders. 



n. 



GENERAL VEGETABLE MORPHO- 

 GRAPH.Y. 



64. The FOEMS occurring in the vegetable kingdom are 

 not reducible to such strictly mathematical surfaces as are 

 seen in the crystals of rock-salt, common salt, and sundry 

 other minerals. 



In describing the forms of plants, or their parts, we 

 compare them either with simple geometrical figures or 

 with familiar objects, as a bell, a cup, urn, top, etc. 



Of strictly geometrical or mathematical forms, we^nd 

 in plants perhaps only one^he spherical form of the cell. 



In Botany, regular forms are those which may be 

 divided into two equal parts, by more than one section 

 coinciding with the axis ; symmetrical forms, on the other 

 hand, are those which can be divided only by one such 

 section into true halves, each related to the other, like the 

 right and left hand. Thus mal/oaceous, rosaceous, cam- 

 panulate corollas are called regular, like a cube, a sphere, 

 etc., in mathematics. A papilionaceous flower, on the 

 other hand, or a ringent corolla, is said to be symmetrical. 



65. All the. forms oocuEKicfG in the vegetable king- 

 dom AEE SOLID BODIES — that is to Say, they present the three 

 dimensions of space which all solid bodies present — ^namely, 



