346 



STARCHES OF GRAMINACE^. 



Curve of Reaction-Intensities of Starch of Zea mays 

 var. everta (White Rice). 



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

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



With seleniie the quadrants are usually well defined, irregular in shape, and imequal in size. 

 The colors are generally pvire. 



Iodine Rcac(ro7is. 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 gelatinised, 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. 



Staini7nj Reaclio7is.- 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 

 lightlj' and unevenly stained. The color is rather lighter 

 than in Golden Queen. 



With safi-ani7i 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 unevenly 

 stained. The color is lighter than in Golden Queen. 



Temperature Reaction. The temperature of gcla- 

 tinization is G1.5 to G3 C., mean 62.25. 



Effects of Various Reagents. The grains begin to 

 react at once with 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 acid the reaction begins at once. A few grains are 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 ai'o gelatinized in 1 

 minute, most in 33/2 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 13 2 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). (Plato 1, figs. 1 and 2. Chart 3.) 



Histological Characteristics. In form the grains an; 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, jrosition, and number of the pressure facets. The conspicuous forms are the poly- 

 gonal with four to six facets. There are also roimd or nearly round, ovoid, hemisi)herical, triangular 

 forms with much-rounded angles and various irregular forms. 



The hiliwi 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 Assuring. 



The lamella: are not demonstrable. 



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

 22 by 16;u and 20 by 20^. The common size is 12^. 



Polariscopic Properties. The figure is usually centric, distinct, ami 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. 



