GKNUS ZEA. 



347 



P5 CI PA CA 

 ^ PCP3 



Curve of Reaction-Intensities of Starch of Zea mays 

 var. indurata (North Dakota). 



The 



With selenite the quadrants are not well defined, fairly regular in form, and usually equal in 

 size. The colors are generally pure. 



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

 with a 0.125 per cent solution they color lightly. The color is slightly more than Golden Queen. 

 After heating 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 gelatinized grain-residues not at all. The cap- 

 sules all color red-violet with an excess of iodine. 



Staining Reactions. — The grains are unevenly stained 

 at once with gentian violet, the body of the grain very 

 lightly; but when the fissures are broad the grains are 

 frequently stained deeply. Small globular bodies ad- 

 hering to the larger grains stain deeply. After remaining 

 in the solution for 30 minutes there is very little change. 

 The color is light and the same as in Golden Queen. 



With safranin the grains are unevenly stained at 

 once, the body of the grain lightly; but if fissures are 

 marked they stain deeply. Small globular bodies which 

 stain deeply are adherent to the grain. After remain- 

 ing in the solution for 30 minutes they remain lightly 

 stained, with exception of the deep color sometimes 

 found at the fissures. There is an occasional oval grain 



noted with two longitudinal branched fissures, and these grains are also slightly stained 

 color is slightly deeper than in Golden Queen. 



Temperature Reaction. — The temperature of gelatinization is 66° to 67° C, mean 68°. 



Effects of Various Reagents. — With chloral hydrate-iodine the grains begin to react at once. A 

 few are gelatinized in a minute, nearly all in 5 minutes, and all in 10 minutes, with rare exceptions. 

 The reaction is qualitatively the same as in Golden Queen. 



The reaction begins at once with chromic acid. A few grains are dissolved in 40 seconds and all 

 The reaction is qualitatively the same as in Golden Queen. 



The reaction with pyrogallic acid begins at once. Some grains are gelatinized in 30 seconds and 

 all in 1^'2 minutes, witli the exception of a few scattered grains (one in several hundred) in which 

 the reaction is complete in 8 minutes. The reaction is qualitatively the same as in Golden Queen. 



The reaction with ferric chloride begins at once. A few grains are gelatinized in 2 minutes, 

 nearly all in 6 minutes, and all in 15 minutes. The reaction is qualitatively the same as in Golden 

 Queen. 



The reaction begins at once with Purdy's solution. A few grains are gelatinized in a minute, 

 and only a few scattered grains are fully gelatinized in 30 minutes, and a very few within an hour. 

 The reaction is qualitatively the same as in Golden Queen. 



STARCH OF ZEA MAYS VAR. INDURATA (COMPTON'S EARLY). (Plate 1, figs. 1 and 2. Chart 4.) 



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

 some in aggregates and clumps. The aggregates consist of from two to five components. There are 

 clearly defined pressure facets on nearly all the isolated grains. The grains are usually quite irreg- 

 ular, owing to pressure facets which vary in size, shape, and number. The conspicuous forms are 

 the polygonal with four, five, or six facets, oval, round, or nearly round. There are also a few hemi- 

 spherical, dome-shaped to hemispherical, and triangular forms with rounded angles. 



The hilum is a small or large round spot or irregularly shaped cavity, centric or slightly eccen- 

 tric, antl usually fissured. The fissures are commonly three in number, straight, narrow, and radi- 

 ating from a cavity. There is sometimes but one straight, narrow fissure. A few grains were deeply 

 and irregularly fissured. 



Tlie lamellae are not demonstrable. 



The grains vary in size from the smaller, which are 4 by 4;u, to the larger, which are 22 by 22/i 

 or 18 by 14/i. The common size is 14/tt. 



in Z]/2 minutes. 



