86 



CELLULAR TISSUE. 



guard-cells, is free from wax-covering, the stoma is as it were shut oflf from this 

 by the ring. Other species of Strelitzia have a similar ring, though in form and 

 distribution of rods they differ from S. ovata. 



The structure and development of the wax coverings and intramural wax have been 

 described by the author of this book in a longer treatise (Bot. Ztg. 1871). There also 

 the very limited older literature on this point is quoted. Later Wiesner made two 

 additions (Bot. Ztg. 1871, p. 769). For various details we must refer to these special 

 works. We can here add but little to what has been said above. 



The internal structure of the wax coverings, which in the rods is indicated by the 

 striation, i.e. by the presence of longitudinal layers of alternately unequal optical 

 properties, attains in the thick layers a complicated differentiation. In the investigated 

 material of Klopstockia cerifera Karst. (Fig. 30) the covering attained a thickness of 



0.66 mm. Above each stoma it is perforated 

 by a perpendicular canal S-S' which contains 

 air and fungal hyphae. It is composed of pris- 

 matic pieces, of which each fits exactly over one 

 epidermal cell, and which are not arranged sepa- 

 rately side by side, but are connected directly 

 by a homogeneous intercalary or fundamental 

 mass. This appears in thin sections as a trans- 

 parent limiting band between the sides of the 

 prisms. Each of the latter shows internally (i) a 

 rich and delicate stratification parallel to the 

 outer surface of the contiguous epidermal cell, 

 dark and clear layers alternating, of which the 

 latter resemble the hyaline limiting bands; (2) 

 darker longitudinal bands perpendicular to the 

 strata and to the surface, these are denser the 

 nearer they run to the lateral surfaces of the 

 prism in the hyaline substance; (3) delicate 

 striations which run from the lateral faces 

 obliquely at an angle of 3o°-4o°, slightly curved, 

 towards the epidermis and the median line of 

 the prism, but do not reach the latter. Under a 

 low power they are not seen, while the longi- 

 tudinal striations are only slightly visible, the 

 strata appearing to be continuous from one 

 prism to the other : as in Fig. 30. 



The deposits of wax on species of Chamse- 

 dorea, Euphorbias, Panicum turgidum, and the 

 fruits of Myrica cerifera, show striation and 

 stratification of a simpler sort. The wax cover- 

 ing of the fruit of Benincasa cerifera is pecu- 

 liarly complicated; it consists of a reticulate 

 layer, and bundles of rods united across one another like a trellis. 



The layer of wax on the young leaf of Corypha cerifera was first described by 

 Wiesner (A c), and, as I think, not correctly in all the particulars. I find in the material 

 which I received through the kindness of Professor Wiesner the following structure. 

 Both leaf-surfaces are covered by a white layer, in which there appear under a higher 

 power three constituent forms: (i) a clear transparent ground substance; in this (2) 

 dark (blueish) spots, and (3) much clearer more transparent points in the form of very 

 various figures, sometimes narrow slit-like, sometimes round. The latter clear spots 

 appear as cavities in the substance, and may here be so called. Thin transverse sections 



FIG. 30.— (116) Klopstockia cerifera; intemode of 

 stem, transverse section, e — f epidermis; .? — .S"" stoma, 

 with two small guard-cells between the two larger sub- 

 sidiary cells ; w wax covering over the epidermis, over 

 which it fits ; SS' the canal leading to a stoma. 



