146 



A TEXT-BOOK OF BOTANY. 



water and the mixture filtered, the filtrate does not give a reaction 

 with iodine solution ; if, on the other hand, the starch is previously 

 triturated with sand and then with water, the filtrate becomes blue 







* .> " 



FIG. 91. Larger grains of various starches as viewed through the micropolariscope 

 when mounted in oil: A, potato (70-80 M); B, wheat (30-40 M); C, ginger (30-50 M); D, 

 galangal (45-55 /n); E, calumba (40-60 M); F, zedoary (50-75 ft); G, maranta (35-50 /t); 

 H, colchicum (10-20 n); I, corn (20-25 /*); J, cassava (20-35^ ); K, orris root (30-35 /n). 



on the addition of iodine solution. It appears that in the latter 

 operation the wall of the grain is broken and the soluble starch 

 present in the grain is liberated. 



