EPIDERMIS. 179 
strongly thickened on the outer side than on the inner’ (Figs. 
83, 85, 63, 109, 129, 155). Occasionally the outer wall is even 
of quite remarkable thickness (Caryophylli, Macis, Fig. 160). 
An example where this is not the case is presented by the epi- 
Fic. 87.—Transverse section through Semen Paradisi (Grains of Paradise); f, epider- 
mis; gh, testa of the seed. 
dermis of Hyoscyamus seeds. Here the outer wall of the epidermal 
cells of the testa is formed exclusively of the delicate cuticle. 
The outer wall of the epidermis cells is always covered by the 
Fic. 88.—Semen Hyoscyami, .A, Transverse section; a, cuticle; b, epidermis; c, testa ; 
d, albumen cells; 0, fatty oil. B. Tangential section through the cells of the epidermis, 
cuticle (see page 161 and Figs. 155, 160, 63, 128, 161), usually a 
delicate * film, insoluble in sulphuric acid, impenetrable by water 
‘The delicate epidermal cells of the seeds of Cydonia me Linum, 
which produce mucilage, form an exception (Berg’s ‘‘ Atlas,” xlvi., 122, 
128). 
*Compare Tschirch, ‘‘ Ueber einige Beziehungen des anatomischen 
Baues der Assimilationsorgane zu Klima und Standort,” Linnea, ix. 
(1881), 139, 
