218 PROCEEDINGS OF SOCIETIES. 



epidermis on both sides of the leaf was shown to be composed 

 alike of cells with sinuous margins (colpencbyma), with the addi- 

 tion to the epidermis on the under surface of oval stomata, and 

 shortish, smooth, taper, slightly curved hairs. Throughout the 

 parenchyma of the leaf were sphseraphides, thickly studded, and 

 with a mean diameter of about toVo^'^ ^^ ^^ ^^^^ 5 ^^^ ^^^6 and 

 there were short strings of similar sphjeraphides, only about half 

 as large, on the fibro-vascular bundles. The composition of the 

 sphaeraphides appears to be chiefly oxalate of lime. They are not 

 easy to find, in' consequence of the density and opacity of the 

 surrounding parts ; and this is probably the reason why these 

 beautiful crystals have hitherto escaped discovery. 



Value of Potash m Histological Phytotomy. — At the same time 

 he remarked that the value of potass in separating the fibres, 

 membranes, or cells, and clearing parts of plants for microscopical 

 investigation, seems to have been insufiiciently appreciated. He 

 showed, for example, that by treatment with cold solution of this 

 alkali, and still better by boiling in it portions of the tea leaf, the 

 epidermis could easily be detached from both sides, leaving quite 

 distinct the interveniug layer of parenchyma and nerves, and thus 

 beautifully exposing the sphaeraphides. He had found the potass 

 equally useful in disclosing the short prismatic crystals in legu- 

 minous and many other plants, and in examination of the tea of 

 commerce ; so that the heretofore refuse of the teapot may be made 

 a very interesting subject for microscopical inquiry. 



