350 



STARCHES OF GRAMINACE^E. 



Chart No. 6. 



I GV 

 S 



PS CI PA I 

 ~ PC PS 



The grains vary in size from the smaller, which arc 2 by 2^, to the larger, which are IG by 12/j. 

 The common size is 8/1. 



Polariscopic Properties. — The figure is usually centric, distinct, regular, and for the most part 

 fairly clear-cut. The lines composing it are straight, as a rule, and commonly placed at right angles, 

 but in a few grains at varying angles. 



The degree of polarization is fair. It varies somewhat in different grains, but not in dif- 

 ferent aspects of the same grain. It is less than in Golden Queen. 



With selenite the quadrants are generally well defined, irregular in form, and usually unequal 

 in size. The colors are not ordinarily so pure as in Early Learning. 



Iodine Reactions. — With a 0.25 per cent Lugol's solution the grains all color a fairly deep violet; 

 with a 0.125 per cent solution they color lightly. The color is slightly deeper than in Golden 

 Queen and the same as in Early Leaming. After heat- 

 ing in water until all the grains are completely gelatinized, 

 the solution colors fairly and the gelatinized grains very 

 deeply on the addition of iodine. After boiling for 2 

 minutes the solution colors very deeply, but the gelati- 

 nized grain-residues not at all. The capsules all color 

 red-violet with an excess of iodine. 



Staining Reactions. — With gentian violet the grains 

 are lightly stained at once. After remaining in the solu- 

 tion for 30 minutes there is very little change. The 

 color is deeper at the fissure. The color is about the 

 same as in Golden Queen and in Early Leaming. 



The grains are lightly stained at once with safranin. 

 After remaining in the solution for 30 minutes there is 

 very little change. The color is deeper than in Golden 

 Queen and about the same as in Early Leaming. 



Temperature Reaction. — The temperature of gela- 

 tinization is 66° to 67.5° C., mean 66.75°. 



Effects of Various Reagents. — With chloral hydrate- 

 iodine the grains begin to react at once. Most of them are 

 gelatinized in a minute and all in 7 minutes. The reaction is qualitatively the same as in Golden Queen. 



The reaction begins at once with chromic acid. Some grains are gelatinized in 35 seconds and 

 all are dissolved in a minute. The reaction is qualitatively the same as in Golden Queen. 



The reaction with pyrogallic acid begins at once. A few grains are gelatinized in 30 seconds 

 and all in a minute. The reaction is qualitatively the same as in Golden Queen. 



The grains begin to react at once with ferric chloride. A few grains are gelatinized in a minute, 

 most in 3 minutes, and all in 8 minutes. The reaction is qualitatively the same as in Golden Queen. 



With Purdy's sohdion the reaction begins at once. A few small grains are gelatinized in IJ^ 

 minutes, about one-fifth in 30 minutes, and gelatinization is very incomplete in an hour. The re- 

 action is qualitatively the same as in Golden Queen. 



STARCH OF ZEA MAYS VAR. SACCHARATA (STOWELL'S EVERGREEN, A DENT SWEET CORN). 



(Plate 1, figs. 1 ami 2. Chart 7.) 



Histological Characteristics. — In form the grains are simple and isolated, with the exception of a 

 few aggregates and clumps. The surface is generally irregular, owing to pressure facets which vary 

 in number, form, and position. The conspicuous forms are polygonal which usually have five or 

 six facets, oval, and round, both of which are often faceted. There are also some hemispherical and 

 triangular grains, and dome-shaped to hemispherical. 



The hilum, when not fissured, is a fairly small or large round spot or irregularly shaped cavity 

 which is centrally or slightly eccentrically situated. It is often fissured and there is usually an 

 arrangement of three straight, narrow lines which proceed from a common center. There are some 

 grains which are very deeply and irregularly fissured. 



The lamelloB are not demonstrable. 



The grains vary in size from the smaller, which are 4 by 4/<, to the larger, which are 20 by 19)u. 

 The common size is 14;u. 



Curve of Reaction-Inlenaities of Starcfi of Zea maya 

 var. indentata (Hickory King). 



