26 PRIMAKY DIVISJONS, ETC. 



slightest pressm-e tliis fluid is injected through the tube into the 

 wound made by its point. Ex. nettle. 



43. Prickles (Fig. 3) are also expansions of the epidermis, 

 consisting of hardened cellular tissue (29, e). They are appen- 

 ded to the cuticle alone, and are stripped off with it. Unlike 

 the thor7i (171), they have no connection with the wood, nor do 

 they disappear by cultivation. Ex. rose, bramble. (Rubus.) 



44. Glands (Fig. 3) are minute bodies of cellular tissue, situ- 

 ated on various parts of the plant, generally serving to elaborate 

 and discharge its pecuhar secretions, which are oily, resinous, 

 saccharine, acrid, &c. 



a. They are either sessile, as in the cassia; or mounted upon a stipe, as in the 

 passion flower ; or imbedded in the leaf, causing it to appear pimctate, as in the 

 leaf of the lemon. Often the gland appears to be merely the expansion of a hair, 

 either at its base or its summit. Such are called glandular hairs. 



45. Analogous to glands, are those cavities formed in the cel- 

 lular tissue, to serve as receptacles of secretion. Examples are 

 seen in the rind of the orange and lemon, containing minute 

 drops of a fragrant volatile oil. The turpentine of the fir balsam 

 is stored up in large reservoirs of this kind. 



CHAPTER III. 



PRIMARY DIVISIONS OF TBE VEGETABLE KINGDOM. 



46. The vegetable kingdom has long been considered by 

 botanists under two great natural divisions, namely, Phjenoga- 

 MiA, or Flowering Plants, and Cryptogamia, or Flowerless 

 Plants. 



47. Besides the obvious distinction made by the presence or 

 the absence of the flower, these divisions are further distin- 

 guished by their structiure. The PhsBUOgamia abound with the 

 lig7ieous and vascular tissue, while the Cryptogamia consist 

 more generally of the cellular. Hence, the former are also called 

 Vasculares, and the latter Cellulares. 



