420 



STARCHES OF POLYGONACE^. 



Effects of Various Reagents. With chloral hydrale-iodine the reaction begins at once. All l^ut 

 rare resistant grains arc gelatinized in a minute, and all in 5 minutes. It is the same qualitatively 

 as that of the grains of American buckwheat. 



The reaction with chromic acid begins at once and is over in 45 seconds. It is the same quali- 

 tatively as that of the grains of American buckwheat. 



The reaction with pyrogallic acid begins in 15 seconds and is over in 1% minutes. It is the same 

 qualitatively as that of the grains of American buckwheat. 



With ferric chloride reaction begins in a few grains in a minute. It is over in nearly all in 10 min- 

 utes and in all in 20 minutes. It is the same qualitatively as that of the grains of American buckwheat. 



Eeaction with Purdy's solution begins in many grains in 30 seconds to 1 minute and is over 

 in four-fifths in 15 minutes, with an incomplete reaction in an hour. It is the same qualitativelj' as 

 that of the grains of American buckwheat. 



Differentiation of Certain Starches of the Genus Polygonum. 



Histological Characteristics. 

 Conspiawiis Forms. 

 American: Probably solely simple, mostly isolated, iso- 

 lated grains polygonal, sharp or generally much- 

 rounded corners, round; aggregates rod or club- 

 like, oval and irregular in shape. 

 Japanese: Same as in American buckwheat. 



Hilum Form, Number, and Position. 



American: Form usually a cavity from which radiating 

 fissures pass. Position centric or slightly eccentric. 



Japanese: Form same as in American buckwheat. Posi- 

 tion centric or slightly eccentric. 



Lamella; General Characlerislics. 

 American: Not visible. 

 Japanese: Not visible. 



Size. 

 American: From 2 to 14;i, commonly 7m- 

 Japanese: From 2 to 12^, commonly S/i. 



PoLARiscopic Properties. 



Figure. 



American: Centric or slightly eccentric, distinct, usually 



a cross, lines rather fine, generally straight. 

 Japanese: Same as in American buckwlieat. 



Degree of Polarization. 

 American: Fair to rather high. 



Japanese: Fair to rather high, usually slightly higher 

 than in American buckwheat. 



Polarization with Selenite Quadrants and Colors. 

 American: Quadrants clearly defined, commonly slightly 



irregular in shape and size. Colors generally piu-e. 

 Japanese: Quadrants same as in American buckwheat. 



Colors generally somewhat purer than in American 



buckwheat. 



Iodine Reactions. 

 Intensity and Color. 

 American: Light; violet. 



Japanese: Light, less than in American buckwheat; 

 violet, more reddish than in American buckwheat. 



Staining Reactions. 

 With Gentian Violet. 

 American: Very light. 

 Japanese: Very light, same as in American buckwheat. 



With Safranin. 

 American: Light. 

 Japatiese: Light, same as in American buckwheat. 



TEMPER.\TnRE OF GeLATINIZATION. 



American: 63 to 04 C, mean 63.5. 

 Japanese: 64.5 to 05 C, mean 64.75. 



Effects of Various Reagents. 



Reaction with Chloral Hydrate-Iodine. 



American: Begins immediately; complete in all but rare 



resistant grains in a minute, and in all in 8 minutes. 



Japanese: Begins immediately; complete in all but rare 



resistant grains in a minute, and in all in 5 minutes. 



Reaction nrith Chromic Acid. 

 American: Begins at once; comjilete in a minute. 

 Japanese: Begins at once; complete in 45 seconds. 



Reaction with Pyrogallic Acid. 

 American: Begins in 15 to 30 seconds; complete in 3 



minutes. 

 Japanese: Begins in 15 seconds; complete in IJ^ minutes. 



Reaction with Ferric Chloride. 

 American: Begins in a few in a minute; complete in all 



in 35 minutes. 

 Japanese: Begins in a few in a minute; complete in all 



in 20 minutes. 



Reaction with Purdy's Solution. 



American: Begins in many in 30 seconds; two-fifths 

 partially gelatinized in 20 minutes, with an 

 incomplete reaction in an hour in the grains as a 

 whole. 



Japanc.-ic: Begins in many in 30 to 60 seconds; four- 

 fifths completely gelatinized in 15 minutes, with 

 incomplete reaction in an hour in the grains as a 

 whole. 



NOTES ON THE STARCHES OF POLYGONUM. 



The two buckwheat starches were obtained from agricultural varieties which differ very little. 

 In general histological features the grains of the two specimens are not distinguishable from each 

 other, and the differences noted in the degree of polarization and in the reactions with the reagents 

 are slight and fall witliin the limits of error of experiment. However, that the two starches are not 

 identical is suggested especially in the difference in the temperature of gelatinization (1.25) and in 

 the less sensitivity of the American form to all the chemical reagents. 



