26 PRIMARY DIVISIONS, ETC. 



slightest pressure this 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 thorn (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 peculiar 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 punctate, 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 resei-voirs of this kind. 



CHAPTER III. 



PEIMARY DIVISIONS OF TIIE VEGETABLE KINGDOM. 



46. The vegetable kingdom has long been considered by 

 botanists under two great natural di\'isions, namely, Ph.«noga- 

 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 structure. The Pheenogamia abound with the 

 ligneous and vascular tissue, while the Cryptogamia consist 

 almost wholly of the cellular. Hence, the former are also called 

 Vasculares, and the latter Cellulares, 



