GENUS TRITICUM. 



367 



Chart No, 



Gv S T CI 



With selenite the quadrants arc rarely well deflned, and generally unequal in size and irregular 

 in shape. The colors in the large grains are commonly not pure, and this lack of purity occurs in a 

 greater proportion of grains than in the previous preparation. 



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

 to reddish-violet; and with a 0.125 per cent solution they color lightly, and the color deepens slowly. 

 The color is slightly deeper than that of the grains of T. 

 sativum var. vulgare. 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 most of the gelatinized grain-residues 

 very lightly. The capsules, which are much twisted and 

 folded, all color violet with an excess of iodine. 



Staining Reactions. — With gentian violet the grains 

 begin to stain very lightly at once and in 30 minutes they 

 are very lightly stained. The color is the same as that of 

 the grains of T. sativum var. vulgare. 



With safranin the grains begin to stain very lightly 

 at once and in 30 minutes they are lightly stained. The 

 color is the same as that of the grains of T. sativum var. 

 vulgare. 



Temperature Reaction. — The temperature of gelatini- 

 zation is 62° to 63.8° C, mean 62.9°. 



Effects of Various Reagents. — With chloral hydrate- 

 iodine the reaction begins in some of the grains in 15 to 

 45 seconds, and in most of the grains in 5 minutes. About one-fifth are fully gelatinized in 20 minutes, 

 without much further reaction in an hour. The reaction is the same qualitatively as that of the 

 grains of T. sativum var. vulgare. 



The reaction with chromic acid begins in from 10 to 20 seconds and is over in 2 minutes. It is 

 the same qualitatively as that of the grains of T. sativum var. vulgare. 



The reaction begins in 20 seconds and is over in 2 minuteswith pyrogallic acid. 

 qualitatively as that of the grains of T. sativum var. vulgare. 



With ferric chloride the reaction begins in a few grains in a minute. Nearly all are completely 

 gelatinized in 50 minutes and all in an hour. The reaction is qualitatively the same as that of the 

 grains of T. sativum var. vulgare. 



The reaction with Purdy's solution begins in some of the grains in 20 seconds, and in many in 

 a minute. About four-fifths are completely gelatinized in 5 minutes, nearly all in 10 minutes, and 

 all in 15 minutes. The reaction is qualitatively the same as that of the grains of T. sativum var. 

 vulgare. 



Differentiation of the Starches of the Genus Triticum. 

 HisTOLoaicAii CHABACTEKisTica. HiSTOLoaicAL CHARACTERISTICS. — Continued. 



Curve of Reaction-Intensities of Starch of Triticum 

 sativum var. dicoccum. 



It is the same 



Conspicuous Forms. 



sativum var. vulgare: Simple, large grains arc nearly 

 round, oval, and irregularly ovoid; minute grains 

 globular and ovoid. 



sativum var. dicoccum: Same a? in T. sativum var. 

 vulgare, but minute grains are very much less 

 nuniei'ous and the larger grains vary more in form 

 and arc more irregular in outline. 



Hilum — Form, Number, and Position. 



T. sativum var. vulgare: Form usually not visible; in 

 large grains there may be a cavity or cleft and 

 occasionally radial fissures; in minute grains a 

 clear spot. Centric or slightly eccentric. 



T. sativum var. dicoccum: Same as in T. saliviim var. 

 vulgare. Position centiic or slightly eccentric. 



Lamelke — General Characlerislics and Number. 



T. 



sativum var. vulgare: Rarely visible; fine, regular, 

 continuous rings. Occasionally 8 to 10 on the 

 larger grains. 

 T. sativum var. dicoccum: Same as in T. sativum var. 

 vulgare, but they are visible on a larger proportion 

 of grains. Occasionally 10 to 14 on the larger 

 grains. 



Size. 



T. sativum var. vulgare: From 2 to 38^, usually 20/i. 

 T. sativum var. dicoccum: From 2 to 40f<, usually 22tt. 



PoLARLScoPic Properties. 



Figure. 



T. sativum var. vulgare: Usually centric, commonly fairly 

 distinct, generally regular, lines usually straight. 



