OF BACCHARIS GENISTELLOIDES 687 
and excessive dryness come to light on an examination of the 
anatomy and physiology of the plant. 
THE EPIDERMAL SysTEM 
The protective system of the plant is very well developed. 
There is a considerable covering of wax over the whole plant 
(cf. f 9). In addition, the epidermal cells are cuticularized 
both without and within; and particularly in the younger por- 
tions, the surface is covered with peculiar hairs, of which usually 
only the end-cells project above the wax. The stomata are exserted 
and are apparently sensitive. The zaxis laid down in the form 
of irregular plates fitted together into a sort of mosaic. In the 
younger portions, to about 3-7 cm. back of the tip, the waxy 
covering is very thick, while the outer layers are shed in the form 
of powdery scales. Its very ready solubility in ether indicates its 
fatty nature. The cwufin is present in a layer over the entire plant 
even up to the very tip of the growing point, though, naturally, it 
has less thickness here than in the older parts of the plant. The 
surfaces of the leaves present on the lower parts of the plant are 
more heavily cutinized than either the wings or the stem. 
The hazrs almost always arise in pairs from two adjacent epider- 
mal cells. In most of the members of this family, as Vesque,* whose 
observations have been confirmed by more recent investigators, 
points out, two kinds of hairs are to be found: glandular hairs and 
mechanical hairs. Both kinds are present in this plant. The gland- 
hairs, which are composed of double series of from 3-5 cells each, 
differ from those mentioned by Vesque and Solereder + in that all 
but the end-cells contain chlorophyl. The cutin is but slightly 
raised by the not very abundant secretion, the nature of which has 
not been any more definitely determined than that it is odorless 
and soluble in ether (f 4). That the secretion of wax is to be 
assigned to the epidermal cells in general, and not particularly to 
these hairs, seems probable from the fact that few or none of the 
hairs are to be found on the older portions of the plant, where, 
nevertheless, the wax is abundant. 
Ann. Sci. Nat. Bot. VII. 1: 
* Vesque, T. Caractéres des * * * Gamopétales. 
183. I 885. 
t Solereder, H. Systematische Anatomie der Dikotyledonen. 515 ff. 1899. 
