346 



STARCHES OF GRAMINACE^. 



I GV 

 S 



CI PA 

 PC PS 



Curve of Reaction-Intensities of Starch of Zea mays 

 var. cverta (White- Rice) . 



The degree of polarization is fairly high. It varies somewhat in different grains, but not much 

 in different aspects of the same grain. It is slightly less than that of the grains of Golden Queen. 



With selenite the quadrants are usually well defined, irregular in shape, and unequal 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; with a 

 0.125 per cent solution they color lightly. The depth of color is the same as that of the grains of 

 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 solu- 

 tion colors very deeply, but the gelatinized grain-resi- 

 dues not at all. The capsules all color a red-violet with 

 an excess of iodine. 



Staining Reactions. — The grains when viewed in 

 masses show a slight tint of violet with gentian violet. 

 After remaining in the solution for 30 minutes they are 

 lightl}' and unevenly stained. The color is rather lighter 

 than in Golden Queen. 



With safranin the grains, when viewed in masses, 

 show a slight tint of pink at once. After remaining in the 

 solution for 30 minutes they are very lightly and imevenly 

 stained. The color is lighter than in Golden Queen. 



Temperature Reaction. — The temperature of gela- 

 tinization is 61.5° to 63° C., mean 62.25°. 



Effects of Various Reagents. — The grains begin to 

 react at once wth chloral hydrate-iodine. Most are gela- 

 tinized in a minute and all in 5 minutes. The reaction is qualitatively the same as in Golden Queen. 



The reaction with chromic acid begins at once. A few grains are dissolved in 25 seconds and 

 all in 80 seconds. The reaction is qualitatively the same as in Golden Queen. 



With pyrogallic add the reaction begins at once. A few grains arc gelatinized in 25 seconds 

 and all in 45 seconds. A bubble is sometimes formed at the hilum. 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 1 

 minute, most in 3J^ minutes, and all in 10 minutes. The reaction is qualitatively the same as in 

 Golden Queen. 



The reaction with Purdy's solution begins at once. A few grains are gelatinized in IJ^ minutes 

 and about one-third in 30 minutes. There was little further reaction in an hour. The reaction 

 is qualitatively the same as in Golden Queen. 



STARCH OF ZEA MAYS VAR. INDURATA (NORTH DAKOTA). (Plate 1, figs. 1 and 2. Chart 3.) 



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

 few in aggregates and clumps. The surface of the grains is generally very irregular, owing to the 

 variations in size, position, and number of the pressure facets. The conspicuous forms are the poly- 

 gonal with four to six facets. There are also round or nearly round, ovoid, hemispherical, triangular 

 forms with much-rounded angles and various irregular forms. 



The hilum is a small round spot or irregularly shaped cavity, usually centric. There is com- 

 monly present at the hilum three fissures which radiate from a central cavity. In some grains there 

 is one fissure, and in a few there is a very extensive deep and irregular fissuring. 



The lamelke are not demonstrable. 



The grains vary in size from the smallest, which are from 2 by 2/i, to the largest, which are 

 22 by 16/1 and 20 by 20ju. The common size is 12fi. 



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

 cut, and generally regular. The lines composing it are sometimes slightly curved and generally 

 at right angles to one another. 



The degree of polarization is fairly high. It varies somewhat in different grains, but not in 

 different aspects of the same grain. It is slightly higher than in Golden Queen. 



