350 



STARCHES OP GRAMINACE^. 



P I GV 

 S 



Chart No. 6. 



CV S T CI C A 





PS CI PA 

 ~ PC PS 



The grains vary in size from the smaller, which arc 2 by 2/li, to the larger, which are 10 by 12ju. 

 The common size is 8;u. 



Polariscopic Properlies. 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 polarizalion 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 selcniie the quadrants are generally well defined, irregular in form, and usually unequal 

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



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 tliey color lightly. The color is slightly deeper than in Golden 

 Queen and the same as in Earl.y Leaming. After heat- 

 ing in water until all the grains are completely gelatinized, 

 the solutioji 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 wdth 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 safrani.n. 

 After remaining in the solution for 30 minutes there is 

 very little change. The color is deeper than in Golden 

 Queen and al)out the same as in Early Leaming. 



TemjJeralure 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 qualitativolj' 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 solution the reaction begins at once. A few small grains are gelatinized in 1}4 

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

 action is qualitatively the same as in Goltlen Queen. 



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



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



Histological Characteristics. In /or? the grains ai'e 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 ilome-shaped to hemispherical. 



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

 which is c(>ntrally or slightly eccentrically situated. It is often fissured and there is usually an 

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

 grains which are very deeply and irregidarly fissured. 



The lamella: are not demonstrable. 



The grains \ar}- in size from the smaller, which are 4 by 4/(, to the larger, which are 20 liy HV. 

 The common size is 14/.1. 



Curve of Reaction-Intensities of Starch of Zea mays 

 var. indentata (Hickory King). 



