4 STUDIES IN HISTOLOGY. 



(c) Remove a moderately thin film from the young stem or 

 branch of some Cactus, and examine the exposed surface of the 

 epidermal cells for cntinization (156 and 224). Apply any 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) fruit of plum, juniper, or Myrica cerifera (Bayberry). 



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

 elastica (India-rubber plant), noting the epidermis and cystoliths 

 (see 164 and Fig. 6). 



(f) Examine the examples of multiple epidermis afforded by 

 many of the cultivated species of Begonia. 



Trie-homes, (a) Examine the velvety petals of an}* flower, 

 and compare their very short trie-homes, or hairs, with those on 

 downy, rough, and bristly stems and leaves. 



(b) Examine also a vertical section of a young rose-prickle. 

 The variety of glandular trichomes at hand in an}' locality 



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

 selection. 



(c) Root-hairs are easily obtained by allowing the seeds of 

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

 filtering-paper, or even on moist glass. 



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

 crometer eye-piece (1 1) is very necessary. By its employment 

 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. 



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

 by the tips of the teeth of the leaves from some species of Fuchsia. 

 Sections showing their constituent cells are best made vertically 

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

 Garden Nasturtium, also gives good examples. 



(J) Compare with these water-pores the irregular rifts in the 

 leaves of some grasses ; for instance, Indian corn. 



