CHAPTER VII. 

 THE EPIDERMIS (CoNTU.) HAIRS MUCILAGE WAX. 



PRINCIPAL, MATERIALS USED. 



Leaves of Wallflower ; fresh. Also young shoots ; in alcohol. 



Leaves of Matthiola annua (Ten-week Stock) ; fresh. 



Flowers of Pansy ; fresh. 



Flowers of Verbascum nigrum (Mullein) ; fresh ; also, 



Leaves of V. thdpsiforme, or V. tlwpsus ; fresh. 



Leaves of Shcpherdia canadensis, or of Elaeaffnus angustifolia; fresh. 



Twigs of Rosa ; fresh. 



Young stems and leaves of Stinging-nettle ( Urtica dioica) ; fresh. 



Petioles of Primula sinensis ; fresh ; or of Pelargonium zonale. 



Young shoots of Pansy ( Viola tricolor) ; fresh. 



Winter buds of Horse-chestnut (&sculus Hippocastanum) ; fresh, and in 



alcohol. 



Leaves of Echeveria, and Eucalyptus ylobulus ; fresh. 

 Nodes of stems of Sugar-cane (SaccJiarum) ; fresh. 



PRINCIPAL REAGENTS USED. 



Acetic acid Sulphuric acid Hydrochloric acid 20 per cent, chromic acid 

 Rosaniline violet. 



WE are already acquainted with the root-hairs of the Frogbit, 

 Hydrocharis morsus-rance, and as root-hairs are always, like these, 

 unicellular sacs, we need not further investigate them. We have 

 also seen the epidermal cells of numerous petals elongated into 

 conical papillae (Tropceolum, fiosa), and also the staminal hairs 

 of Tradescantia, threads formed of barrel-shaped, swollen cells 

 (Fig. 14) ; lastly also the hairs of Cucurbita, simple pointed 

 threads arising from a multicellular base. Plant hairs of various 

 forms are therefore already known to us ; it is, however, worth 

 while to amplify our special knowledge of them. 



Hairs of Wall-flower. On the leaves and stems of Cruciferae 

 we find very many forms of much-branched unicellular hairs. On 



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