98 



VII. TBICHOMES WAX. 



forms, with transitions. Two distinct types can be recognised, 

 conical and capitate. The conical hairs are either (1) delicate 

 and unicellular, (2) stouter, and with one or two partitions, the 

 septum, where solitary, being commonly quite close to the outer 

 line of the epidermis, or (3) very long and tapering, with many 

 cross septa, and a distinctly bulbous base, raised upon a wart- 

 like outgrowth, the cells of which show radial arrangement. The 

 capitate hairs are (1) glandular hairs with a round head-cell on a 

 short stalk, 2-3 cells long, (2) glandular hairs with an obovate 

 head-cell set somewhat obliquely on a short stalk ; (3) doubtfully- 

 glandular with a large pear-shaped head-cell on a long 2-3 celled 

 stalk. Between these forms various intermediate states exist. 

 These hairs may also be studied in surface-sections ; and in both 

 these and in cross-sections, carefully taken from fresh material, 

 the tapering or conical hairs not infrequently show streaming 

 movements of the protoplasm. 



Stipular Glands of the Pansy. The large stipules of the pansy, 

 Viola tricolor, are very deeply toothed, and bear at the apex of 

 each tooth a beautiful egg-shaped gland. 

 If it is desired to see these not shrivelled, 

 but as in active life, it is necessary to 

 investigate the youngest possible stipules. 

 The gland (Fig. 37) is separated from the 

 edge of the leaf by a somewhat narrowed 

 neck. It consists of two or more rows 

 of elongated cells, forming a core, upon 

 which a single layer of cells is placed, 

 arranged perpendicularly to the surface, 

 and elongated in this direction. The 

 figure shows such a glandular hair in 

 optical longitudinal section. The whole 

 gland is distinguished by its copious pro- 

 toplasmic contents. In these are often 

 to be seen vacuoles filled with cell-sap, 



either singly or in groups. The secretion 

 . Glandular ban- from & J ' 



the stipule of viola tricolm; and consists of a thin layer of resin on the 

 an^mcellular hair close by (x surface Qf ^ ^^ ^ Qf masses Qf 



slime, which raise the cuticle. With 



rosaniline violet the contents of the cells are coloured red, the 

 resin layer blue, the slime masses reddish. 



Glands on the Winter Bud of JEsculus Hippocastanum. A 



