EPIDERMIS. 



[ 239 ] 



EPIPYXIS. 



frequently, on the leaves of Ferns, on those 

 of Hellebore, &c., and appear very pleasing 

 microscopic objects, especially as, in addition 

 to the lines, the stomates at the angles add 

 to the elegance of the pattern. 



Fig. 204. 



Epidermis from petal of the balsam, with stomates, S , 

 The epidermal cells here have elegantly sinuous side-walls. 



Magnified 200 diameters. 



The cuticle not unfreqnently undergoes a 

 change, which at present is not at all under- 

 stood. This is seen on many petals, as those 

 of the Daffodil, and on leaves, as those of the 

 genus Helleborus, Dianthus, &c., when the 

 epidermis is viewed from above, in the form 

 of elevated striae running in various ways 

 over the surface, sometimes converging in 

 the centre of each cell, in other cases running 

 in tortuous lines over the surface, continuous 

 beyond the boundaries of the individual cells. 

 A similar condition of the cuticle occurs upon 

 the HAIRS of many plants, especially of Cru- 

 ciferse, Ranunculacese, Boragineae, &c. This 

 condition is evidently analogous to the equally 

 mysterious states of the outer membrane of 

 PoLLEx-GRAiNS and Spores, where points, 

 ridges, reticulations, &c. of the same kind 

 constantly occur. 



The stomates are found on both surfaces 

 of many leaves of delicate structure, but 

 most abundantly on the lower surface ; in 

 other plants they occur exclusively on the 

 lower face ; in floating leaves they exist only 

 on the upper face; while on submerged 

 leaves none at all occur, and the epidermis 

 here has no very distinct difference from 

 that of young roots. The characters of 

 Stomates are spoken of more at length 



under that head, as also those of Hairs, 

 Scales, Stings, Thorns, Glands. 



The epidermis of the Equisetacese and the 

 Grasses is remarkable for the deposition of 

 silica, apparently in the walls of the cells of 

 the epidermis, to such an extent and so 

 equably, that the whole of the organic mat- 

 ter may be removed by heat or acids, and 

 a perfect skeleton of the structure be ob- 

 tained, composed exclusively of silex, exhi- 

 biting the boundary lines of the epidermal 

 cells and the stomates (the dentate side- 

 walls, with the stomates arranged in linear 

 series, are described in most microscopic 

 books in a very curious manner, from an old 

 paper by Sir D. Brewster). Preparations of 

 this structure are obtained by treating little 

 pieces of the wall of the fistular stem with 

 strong nitric acid, to remove alkalies, and 

 then burning them until quite white on a 

 slip of platinum or very thin glass. These 

 should be mounted in Canada balsam. 



The seeds of many plants are clothed with 

 an epidermis of remarkable character, the 

 cells containing spiral fibres ; this occurs in 

 the Acanthace^, in Collomia, Salvia, 

 &c., and is further treated under those heads 

 and under Hairs and Spiral Struc- 

 tures. 



BiBL. H. von Mohl, The Vegetable Cell 

 (transl. 1852), Linncea, xvi. p. 401 (1842), 

 Verm. Schrift. p. 260, Ann. des Sc. nat. 2 ser. 

 xix. p. 201, ibid. 3 ser. iii. p. 158, Bot. Zeit. 

 V. p. 497 (1847) (transl. Scientifc Memoirs, 

 new series), ibid. vii. p. 593 (1849); Schlei- 

 den, Grundziige der Wiss. Bot. 3 ed. p. 335 

 {Principles, p. 70) ; Brongniart, Ann. des Sc. 

 nat. x\m. p. 427, 2 ser. i. p. Qb ; Link, Elem. 

 Phil. Bot. i. p. 83 ; Wigand, Intercellular- 

 substanz u. Cuticula, Brunswick, 1850; 

 Karsten, Bot. Zeit. vi. p. 729 (1848) ; Cohn, 

 LinnfEa, xxiii. p. 337 (1850); Hartig, En- 

 twickl. der Pflanze, 1843, Ann. des Sc. nat. 

 3 ser. i. p. 352; linger, Bot. Zeit. v, p. 289 

 (1847); Garreau, Ann. des Sc. nat. 3 ser. 

 xiii, 304 ; Mulder and Harting, Mulder's 

 Phys. Chem. (Edinb. transl. p. 4/0. 1849) ; 

 Goldmann, Bot. Zeit. vi. p. 857 (1848); 

 Schacht, Die Pfianzenzelle, p. 89. Berlin, 

 1852. 



EPIPYXIS, Ehr.— A genus of Infusoria, 

 of the family Dinobryina. 



Char. Fixed by a pedicle ; eye-spot ab- 

 sent. 



No cilia, nor appendages. 



E. utriculus (PL 23. fig. 50). Carapace 

 m-ceolate; body filled with yellowish gra- 

 nules; aquatic; length 1-650", 



