LEAVES 269 
tals. In henbane, coca, and senna are found prisms. In bella- 
donna, scapola, and tobacco leaves are found micro-crystals. 
In most leaves no crystals occur. In witch-hazel and tea 
leaves stone cells occur, but in most leaves there are no stone 
cells. In eucalyptus, thyme, jaborandi, buchu, rosemary, and 
white pine leaves are secretion cells; while in belladonna, 
stramonium cells occur. In senna and coca leaves are crystal- 
bearing fibres; most leaves do not have crystal-bearing fibres. 
In chimaphila and uva-ursi there are no outgrowths from 
the epidermal cells. 
In senna, witch-hazel, chestnut, and coca, numerous non- 
glandular hairs occur on the epidermis. In tobacco, belladonna, 
henbane, pennyroyal, peppermint, and spearmint both glandular 
and non-glandular hairs occur on the epidermis. 
When studying leaves there should be considered the ab- 
sence or presence of outgrowths and their nature; the nature of 
the epidermis and, when present, the number of layers of the 
hypodermis; the nature of the stoma, whether raised above, 
even with, or below the level of the epidermis; the number of 
layers, and the distribution, when present, of the palisade 
parenchyma; the form and amount of the spongy parenchyma; 
the absence or presence of secretion cells; the nature and form 
of the fibro-vascular bundles, and the nature and amount of 
the organic and inorganic cell contents. 
