THE CELL SAP. 



121 



on the epidermal tissues, especially those 

 of the leaves. The inner portion of the 



cystohth is free from CaCOs- 



Microchemieally, acids have no effect 

 upon calcium oxalate, while they dis- 

 solve the crystals of calcium carbonate 

 with a formation of gas, bubbles of 

 which may be seen by means of the mi- 

 croscope. 



I?' 



Fiff. 19.— Rhizome Rhei. LocRitudinal section, 

 sp. Vessels, K. Crystal sacs,7Jr starch conducting 

 parenchvma. X. Obliterated parenchyma. 



Calcium sulphate and phosphate are 

 rarely found in crystalline condition. The 

 phosphates are a constant ingredient of 

 plant ash, but are seldom seen in a 

 crystalline form save in a few^ plants. 



Euphorbia cese. 



TITE CELL SAP. It has already 

 been pointed out that in the vacuoles 

 and other spaces left by the retreating 

 protoplasm in the cell cavity, and pene- 



Fig. 20.— Cross section leaf of Hemp, showing 

 C. Carbonate of Calcium crystals (crystoliths), 

 oe, oil glands, sp. Stoma. Sch. mesophyll. 

 (Tschirch). 



trating at times the cell wall and the 

 protoplasm, there is a watery material 

 with an acid reaction. This goes by the 

 name of the cell sap. It contains in so- 

 lutuui many materials Ooth organic and 



inorganic. The soluble organic sub- 

 stances include Inulin, Hesperidin, As- 

 paragin, Aloin, Sugar, Allialoids, Gluco- 

 sides, Acetates, inorganic salts, etc. 



Inulin is an isomer of starch, and, like 

 it, is a reserve material. It is found ex- 

 tensively in the roots of plants of the 

 Compositae, in which it varies from 1~ 

 50 per cent. Inula Helenium has 44 per 

 cent., Taraxacum 20 per cent, Pyre- 

 thrum 50 per cent. Microchemieally it 

 is to be distinguished by its insolubility 

 in alcohol and glycerin. If the fresh 

 roots be placed in these solutions the 

 Inulin will precipitate out in the form 

 of sphaero-crystals, which fill the entire 

 coll, Molisch's test is also of value. A- 



ff 



C 



Fier. 21.— Cross section of Aleppo Gall, showlnj 

 Tannm particles. (Hartwich). 



