348 



STARCHES OF GRAMINACEiE. 



Chart No. 4. 



Polariscopic Properties. The figure is usually centric, distinct, and generally clear-cut. The 

 lines composing it are sometimes bent or slightly curved, and are commonly placed at right angles 

 to one another. 



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

 aspects of the same grain. It is higher than in Golden Queen, and the same as in North Dakota. 



With selenite, the quadrants are not very well defined; they are fairly regular in form and 

 commonly equal in size. The colors are usually pure. 



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

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

 and the same as in North Dakota. 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 and the gelati- 

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

 red-violet with an excess of iodine. 



Staining Reactions.' The large grains stain at once 

 very lightly with gentian violet, but deeper at the central fis- 

 sure. There are some deeply stained, very small globules 

 that are lodged chiefly at the fissiu-es, but which do not re- 

 act with Lugol's solution. After remaining in the solu- 

 tion for 30 minutes the grains show very Httle change. 

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



With safranin the grains stain lightly at once, ex- 

 cepting the fissure and some small globular bodies 

 attached to the larger grains at various points which 

 are sometimes fairly well stained. After remaining in 

 the solution for 30 minutes there is very little change. 

 The color is light, but deeper than Golden Queen. 



Temperature Reaction. The temperature of gelatinization is 08 to 09 C., mean 68.5. 



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

 A few are gelatinized in a minute, most of them in i}^ minutes, and all with rare exceptions in 10 

 minutes. The resistant grains retain a deep old-rose tint for 20 minutes, gradually becoming a 

 reddish-piu-ple in 30 minutes. The reaction is qualitatively the same as in Golden Queen. 



The reaction with chromic add begins in a few seconds. A few grains are dissolved in a minute 

 and all in 33^2 minutes. The reaction is qualitatively the same as in Golden Queen. 



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

 all in 2 minutes, with exception of a few scattered grains (one in several hundred) which are gelati- 

 nized in Z]A minutes. The reaction is qualitatively the same as in Golden Queen. 



With ferric chloride a few grains are gelatinized in 2 minutes, most in 5 minutes, and all in 12 

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



The reaction begins at once with Purdy's solution. A few grains arc gelatinized in 2 minutes, and 

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

 is qualitatively the same as in Golden Queen. 



STARCH OF ZEA MAYS VAR. INDENTATA (EARLY LEAMING). (Plate 1, figs. 1 and 2. Chart 5.) 



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

 a few small aggregates and some clumps. Most of the grains have from one to five or six pressure 

 facets. The surface of the grains is generally irregular, owing to variations in the size, position, and 

 number of the pressure facets. The conspicuous forms are the polygonal, which are usually 4- or 

 5-sided, oval, and round or nearly round. There are in addition some dome-shaped to hemispherical, 

 triangular with rounded angles, and indefinite forms. 



The hilum is a small or large round spot, irregularly shaped, usually centric, and when not 

 fissured is indistinct. When it is fissured there is a small cavity from which two or three rather 

 irregular fissures radiate, and there are in some grains three short, straight, radiating fissures. 



The lamella: are not demonstrable. 



Curve of Reaction-Intensities of Starch of Zea mays 

 var. indurata (Compton's Elarly). 



