STRUCTURE.] HAIE, SCUEF, ETC. 151 



which, as follows from its nature, it leaves behind a certain 

 quantity of resin," &c. 



Link, however, still doubts whether stomates are the air- 

 holes of plants, and consequently the organs of respiration ; 

 he cannot find a distinct connection between the stomates 

 and the chasms in the cellular tissue of the leaves. He can- 

 not understand how organs of so distinct a structure should 

 only lead to mere cavities in the cellular tissue ; and the ob- 

 structing and covering matters which they produce, have 

 always led him to consider them as organs of secretion. He 

 however confesses that the matter is doubtful, and that he 

 should not know what to say, if asked, "What secretions 

 are formed by stomates in which such obstructions are not 

 observed ?" 



In Nepenthes the epidermis in the inside of the pitchers is 

 pierced by a great number of holes, each of which is closed 

 up by a firm thick disc of small cellular tissue, deep brown 

 in colour, and connected with the cavernous parenchym of 

 the pitcher. Of this more will be said under the head of 

 GLANDS. 



The surface of the epidermis is either perfectly smooth, or 

 furnished with numerous processes, consisting of cellular tissue 

 in different states of combination, which may be arranged 

 under the heads of hair, scurf t glands, and prickles. All these 

 originate either directly from the epidermis, or from the cellu- 

 lar substance beneath it; never having any communication 

 with the vascular or ligneous system. 



3. Of Hairs. 



F . 1 5 These (fig. 1 5 .) are minute, 



transparent, filiform, acute 

 processes, composed of cellu- 

 lar tissue more or less elon- 

 gated, and arranged in a 

 single row. They are found occasionally upon every part of 

 a plant, even in the cavities of the petiole and stem, as in 

 Nymphsea and other aquatic plants. In the Cotton Plant 

 (Gossypium herbaceum, &c.) they form the substance which 



