58 



OEGANOGRAPHY. 



and internal; by others, into simple and compojind ; while others 

 again have adopted diiferent classifications. The simplest ar- 

 rangement is into external and internal glands. 



a. External Glands. — These may be again divided into stalJced, 

 and sessile or not stalked. The stalked glands are those which 

 are frequently called glandular hairs. They are formed of a single 

 cell, dilated at its apex by the peculiar fluid it secretes {figs. 136 

 and 137); or of two {fig. 140) or more secreting cells {fig. 141) 

 placed at the end of a hair ; or they consist of a mass of secreting 

 cells {figs. 138 and 139). 



Sessile Glands present various appearances, and consist, like 

 the former, of either one secreting cell {fig. 143), or of two or 

 more {fig. 142). Those with one secreting cell placed above the 

 level of the epidermis are frequently termed papulcB or papillcs. 



Fig. 136. Fig. 137. Fig. 138. Fig. 139. 



Fig. 140. 



Fig. 141. 



Fig. 142. Fig. 143. 



Fig. 136. Stalked unicellular gland of Salvia. Fig. 137. Stalked uni- 

 cellular glandsof Frogsinouth (Antirrhinuvimajus). Fig. 138. Stalked 



many-celled gland ot Ailanthus glandulosa. From Meyen. Fig. 139- 



(Stalked many-celled gland from Begonia platanifolia. From Meyen. 

 Fig. 140. Many-celled hair of Frogsmoutli, terminated by a glandular 

 summit, which consists of two secreting cells. Fig. 141. Stalked gland 

 with four secreting cells. From Meyen. Fig.\i2. Sessile many-celled 

 gland from the common Hop (Humulus Lvpulus), ?ind commonly termed 

 a lupilinic gland. Fig. 143. One-celled sessile glands, termed papuhe 

 ; or papillae. 



It is to their presence upon the surface of the ice-plant that the 

 peculiar crystalline appearance of that plant is due. When 



