98 



MORPHOLOGY OF THE CELL. 



one or more essential oils, forming a thickish liquid ; (2) Resins, 

 which have comparatively little essential oil commingled, and are 

 of various grades of hardness ; (3) Gum-resins, or resins hav- 

 ing more or less mucilaginous or gummy matters. To the latter 

 class are sometimes referred 

 the products left by the diying 



B 



A 



79 



of many milky juices (latex) ; of such, caoutchouc is an ex- 

 ample. All the foregoing substances may be found in single 

 cells, which are of very diverse forms. 



296. Roundish cells of this character are found in the Mag- 

 noliacere and some Composite, etc. Long cells are to be de- 

 tected in some Liliaceae, etc., and they are connected by many 

 intermediate forms with resin-ducts arising from the confluence 

 of several cells. On the other hand, they pass by various gra- 

 dations into structures which are generally referred to the latex- 



FIG. 79. Transverse section through the leaf of Psoraloa hirta ; the epidermis con- 

 sisting of one layer with some of the tissue shown on both sides of the gland: A, very 

 young state in which the secretion is not yet present; B, somewhat older, secretion 

 commencing; C, mature state. (De Bary.) 



FIG. 80. A "gland" in Dictamnns Fraxinella : A, B, early stages; C, mature state; 

 p.p, c, mother-cells of the gland-tissue; rf, the covering layer forming a continuation of 

 the epidermis; o, a large drop of oil. (Rauter.) 



