BOTANY FOR BEGINNERS 



CHAP. 



found. They are always found in vacuoles, and when needle- 

 shaped are called raphides. In many monocotyledonous plants 

 they protect the plant from snails, slugs, &c. 



Sugars. Various kinds of sugars and 

 allied bodies are found in the cell-sap. The 

 principal forms of sugar thus found are 

 grape-sugar and cane-sugar. Grape- 

 sugar is found in the fruit of tile Grape, and 

 Cane-sugar is found in the Sugar-cane and 

 Beetroot. 



EXPT. 83. Scrape a freshly cut surface of a 

 Potato tuber with a knife, and mount the 

 scrapings in water. Examine first with a low 

 power and afterwards with a high power. Note 



(i) The numerous starch grains which appear 

 very bright. Observe the hilum and the stratified 

 appearance of each grain. 



(ii) Run some iodine solution under the cover- 

 glass by holding a piece of blotting paper at one 

 edge of it, and placing a drop of the solution on 

 the other edge. The paper soaks up the water, 

 and the solution takes its place. The iodine stains 

 the starch grains blue. 



(iii) Treat another preparation with chlor-zinc- 

 iodine, 1 which is an acid solution of iodine. The 

 starch grains stain blue, but they also swell up and 

 lose their bright appearance. 



(iv) To a fresh preparation add potash solution. 

 The grains swell. 



EXPT. 84. Cut a section from the Potato tuber 

 and mount in water, examine with a high power 

 and find 



(i) A spurious compound grain, 

 (ii) A true compound grain. 



EXPT. 85. Obtain a few Castor Oil seeds, and expose the pearly 

 endosperm or reserve material by removing the outer covering. Cut a 

 thin section of the endosperm and mount in olive oil. Examine with 

 ths high power. Note 



(i) The aleurone grains or proteids granules, 

 (ii) Find the crystalloid and globoid in the grain. 

 EXPT. 86. Cut sections from a cotyledon of the Almond, and mount 

 in water. 



Observe the bright-looking drops in the water ; they are oil drops. 



1 Chlor-zinc-Iodine (Schulze's solution) consists of a mixture of zinc dissolved in 

 pure hydrochloric acid, and a small quantity of potassium iodide dissolved in water. 

 It is an acid solution of iodine. 



Fii. 115. Cell, with a 

 bundle of Raphides. 

 (X 160.) (S.) 



