82 FART II. ANATOMY AND HISTOLOGY. [ 24 



It sometimes happens that the crystal, or group of crystals, be- 

 comes surrounded by a layer of cellulose attached to the wall at 



one or more points (e.g. 



_^^ leaf of Citrus vulgaris, 



^ < ^=?^c^~I^ : -) pith of Kerria japonica). 

 J^rf^^TrTTTY^ )P c. The Cell-Sap satur- 

 -t ates ~tEe celPwall, the 

 protoplasm, in fact the 

 whole organised struc- 

 ture of the cell ; it also 

 fills the vacuole, when 

 present, in the cyto- 

 plasm. It is a watery 

 solution ^f~the~most va- 

 rious substances. In all 

 cases it holds salts in 

 solution, consisting 

 mainly of alkalineTblises 

 in combination either 

 with inorganic acids, 

 such as the nitric, phos- 

 phoric, or .._snlpliuric 1 _ or 

 with organic acids, such 

 as malic (e.g. apple and other fruits), citric (lemon, etc.), and 

 others. It frequently contains tannin, and nitrogenous substances 

 j, such as asparagin. 



It very commonly 



<F- ^OP' ^W "^ * s r i c k *- su g ar: 



either grape-sugar 



(C 6 H 12 6 ), as in 

 the grape and 

 other fruits, and in 

 fact most parts of 

 plants at particu- 

 lar times ; or cane- 

 sugar (C ]2 H 22 O n ) 

 as in the Sugar- 

 cane, the Maple, 

 and the Beetroot. 



FIG. 67. Crystals of calcium oxalate in the cells of the 

 petiole of a Begonia (x 200) : fc solitary crystals ; dr cluster. 



oC/ 1 



FIG. 66. Part of a section of a grain of wheat, 

 Triticum vv.lga.re; p pericarp; t seed-coat or testa; 

 internal to which are cells belonging to the endo- 

 sperm; the external layer contains small proteid- 

 grains (al) but no starch, the more internal cells con- 

 tain starch-grains am ; n the nucleus. (After Stras- 

 burger : x 240.) 



Jerusalem Arti- 



