THE MULTIPLE EPIDERMIS 



49 



which may represent citlier IcKcophisis or ergastic material are 

 also observable. To study the cuticle and the structure of the 

 walls of the epidermal cells, cut thin trans-sections of the bulb- 

 scale, and mount them in a .1% solution of neutral red.^ If these 

 sections are not overstained, the neutral red will be confined 

 largely to the protoplasts and the walls will be clearly demar- 

 cated. Similar trans-sections, when gently heated in a solution 

 of Sudan TV,^ are particularly suitable for a study of the cuticle 

 which will appear under high magnification as a brilliant red 

 layer continuous over the outer walls of the epidermis. 



2. The leaf blade of the geranium {Pelargonium) or the 

 "German Ivy" {Senicio miknnoidcs). Remove small strips of 

 the loAver {aha rial) epidermis and mount some in water, others 

 in a .IVr solution of neutral red. Note especially the charac- 

 teristic undulate contours of the epidermal cells and the numer- 

 ous stomata. If the geranium epidermis is used, the relationship 

 of the numerous multicellular hairs can be readily studied. 



3. The leaf of Iris sp. IMount strips of the epidermis in water 

 as well as in neutral red and examine carefully under low magni- 

 fication, noting the regularly-arranged stomata and the elongate 

 form of the epidermal cells. Careful focusing will show that the 

 guard cells with their stomata are slightly suidvcn beneath the 

 surface and are overarched by the ends of the epidermal cells 

 adjacent to them. Thin trans-sections of the epidermis should 

 also be secured and treated with neutral red and Sudan IV. 

 These sections will reveal the thick cuticle and the prominently 

 thickened outer tangential walls of the epidermal cells. 



4. Prepared slides of trans-sections of the leaf-blades of lilac 

 (Si/ringa vulgaris) and corn {Zea Mays). Trans-sections cut 

 by hand are often too thick to permit of an accurate examination 

 of the structure of the walls of guard cells. For this reason, 

 a supplementary study should be made of the guard cells as seen 

 in thin stained sections of the forms listed above. 



III. The Multiple Epidermis. — In the leaves of certain angio- 

 sperms, particularly in members of the families Piperaeeae. 

 Begoniaceae and Moraccac, some or all of the cells of the original 



1 Cf. Appendix, p. 142. 

 ~Cf. Apppndix, p. 142. 



