318 WALTER GARDINER. 



be treated with Chlor. Zinc lod. the walls swell; the boundary 

 bordering on the cell lumen becomes more distinct ; and definite 

 granules can be recognised deposited in the substance of the 

 swollen wall. I made several experiments to test the nature 

 of these granules. When the sections are warmed in dilute 

 potash solution, the granules appear to become somewhat 

 aggregated together, and signs of commencing solution can be 

 recognised. When boiled with a 5 per-cent. solution of potash 

 they are totally dissolved, the substance of the cell wall is left 

 quite clear, and its limits sharply defined. When sections are 

 treated with ether, and afterwards with boiling alcohol, consi- 

 derable solution takes place, attended with a clearing up of the 

 structure. These reactions appear to indicate that the granules 

 consist of wax, and, as De Bary' has shown, the presence of 

 wax is of frequent occurrence, not only on the surface of the 

 cuticle, but even embedded in the substance of the cuticularised 

 layers of the cell wall. The presence of these granules appears 

 to explain, in a satisfactory manner, both the difFuseness of 

 outline and the appearance of reticulation. 



In Rhododendron, in the same way, an appearance of stria- 

 tion approaching to reticulation occurs. When examined in 

 Chlor. Zinc lod. it becomes apparent that very great cuticu- 

 larisation of the epidermis has taken place, the cuticularisation 

 extending even to the transverse walls. It is also apparent 

 that the striation is confined to the cuticularised layers, and 

 is separated from the cell lumen by a thin layer of cell wall, 

 which still gives the cellulose reaction. If treated with a 

 solution of ]>otash, the cuticularised portion still shows stria- 

 tion, while the rest of the cell wall becomes clear and tran- 

 sparent. Examination of thin sections mounted in glycerine 

 supports these observations in every way. I need only refer 

 to Sach's 'Text-book'" to show that the occurrence of striation 

 in the cuticularised layers of the cell wall of epidermal cells is 

 a perfectly well known phenomenon. His figure of the ejji- 



I ' Vcgl. Anat.,' Leipziz, 1877, p. 87. 

 - Sach's, loc. cit., p. 35. 



