4 STUDIES IN HISTOLOGY. 



(c) Remove a moderate!}- thin film from the young stem or 

 branch of some Cactus, and examhie the exposed surface of th6 

 epidermal cells for ciitinizatioii (156 and 224). Apply anj- of 

 the coal-tar colors to similar fragments, and note differences 

 of tint. 



(d) Examine the " bloom" (226) on the following: (1) stem 

 of Indian corn, (2) stem of castor-oil plant, (3) leaf of cabbage, 

 (4) frnit of plum, juniper, or M^-rica cerifera (Bayberr}-). 



(«) Make a thin vertical section through the leaf of Ficus 

 elastica (India-rubber plant), noting the epidermis and c^'stoliths 

 (see 164 and Fig. 6). 



(/■) Examine the examples of multiple epidermis afforded by 

 manj- of the cultivated species of Begonia. 



Trichomes. (a) Examine the velvet}' petals of anj- flower, 

 and compare their ver}' short trichomes, or haii's, with those on 

 downy, rough, and bristlj- stems and leaves. 



(6) Examine also a I'ertical section of a young rose-prickle. 



The varietj- of glandular trichomes at hand in anj- locality 

 is so great that no special directions need be given for their 

 selection. 



(c) Eoot-hairs are easily obtained b}- allowing the seeds of 

 flax, or the grains of corn, wheat, etc., to germinate on wet 

 filtering-paper, or even on moist glass. 



Stomata (pp. 70-73). For the proper studj- of these a mi- 

 crometer eye-piece (11) is very necessarj'. By its emploj-ment 

 the dimensions of individual stomata and the number of stomata 

 on a given space can be easily determined. 



Sections of stomata are made best by aid of the processes of 

 imbedding (8). Examination of the table by Weiss (page 71) 

 will afford hints as to the selection of large stomata for examina- 

 tion in section. 



Watir-pores and rifts (242). {a) Water-pores are furnished 

 bj- the tips of the teeth of the leaves from some species of Fuchsia. 

 Sections sliowing their constituent cells are best made verticall}' 

 and lengthwise through the leaf. Tropseolum, or the so-called 

 Garden Nasturtium, also gives good examples. 



(5) Compare with these water-pores tiie iiTegular rifts in the 

 leaves of some grasses ; for instance, Indian corn. 



