368 



STARCHES OF QKAMINACEiE, 



Differeniiation of the Starches of the Genus Triticum. — Continued 

 PoLARiscopic Pboperties. — Continued. Temperatdbe of Gelatinization. 



Figure. — Continued. 



T. ttUimim vox. dicoccum: Same as in T. sativum yar. 

 vulgare, but the lines are on the whole less distinct 

 and show more tendency to he bent or bisected. 



Degree of Polarization. 



T. tativum var. vulgare: Ix)w in the larger grains to fair 



in metlium to small grains. 

 T. satit'um var. dicoccum: Same as in T. sativum var. 



vulgare, but lower on the whole. 



Polarization rvilh Selenile — Quadrants and Colors. 



T. taiimim var. vulgare: Quadrants in the large grains 

 usually not well defined, irregular in shape, and 

 unequal in size; small grains, well defined, regular, 

 and equal. Color in large grains impure, in small 

 grains pure. 



T. sativum var. dicoccum: Quadrants in large grains less 

 well defined, more irregular, and more xinequal 

 than in T. sativum var. vulgare; in small grains the 

 same. Color in large grains more impure than in 

 T. sativum var. vulgare, same in small grains. 



Iodine Rbactigns. 



Intensity and Color. 



T. sativum var. vulgare: Fair; blue-violet to reddish-violet. 

 T. sativum var. dicoccum: Fair, slightly deeper than in T. 

 sativum var. vulgare; blue-violet to reddish- violet. 



Staining Reactions. 



With Gentian Violet. 



T. sativum var. vulgare: Very light. 

 T. sativum var. dicoccum: Very light, same as in T. sativum 

 var. vulgare. 



With Safranin. 



T. sativum var. vulgare: Light. 



T. sativum var. dicocaim: Light, same as in T. sativum 

 var. vulgare. 



T. sativum var. vulgare: 63 to 65° C, mean 64°. 



T. sativum var. dicoccum: 62 to 63.8° C, mean 62.9°. 



EFFEcra OP Various Reagents. 

 Reaction ^oUh Chloral Hydrate-Iodine. 



T. sativum var. vulgare: Begins in some in 1.5 seconds; 



l)artial in half and complete in one-fifth in 30 



minutes; incomplete in an hour. 

 T. sativum var dicoccum: Begins in some in 30 to 45 



secondsj partial in most and complete in one-fifth 



in 20 minutes; incomplete in an hour. 



Reaction mih Chromic Acid. 



T. sativum var. vulgare: Begins in 15 to 30 seconds; 



complete in all in 2% minutes. 

 T. sativum var. dicoccum: Begins in 10 to 20 seconds; 



complete in all in 2 minutes. 



Rea^ion with Pyrogallie Add. 



T. sativum var. vulgare: Begins in most in 30 seconds; 



complete in sJl in 3 minutes. 

 T. sativum var. dicoccum: Begins in all in 20 seconds; 



complete in all in 2 minutes. 



Ferric Chloride. 



T. sativum var. vulgare: Begins in a few in a minute; 



complete in three-fourths in an hour. 

 T. sativum var. dicoccum: Begins in a few in a minute; 



complete in all in an hour. 



Reaction with Purdy's Solution. 



T. sativum var. vulgare: Begins in a few in 20 seconds; 



complete in all in 25 minutes. 

 T. sativum var. dicoccum: Begins in some in 20 seconds, 



in many in 1 minute; complete in all in 15 minutes. 



NOTES ON THE STARCHES OF TRITICUM. 



The wheat starches are closely alike in all respects. Apart from the fact that in T. sativum 

 var. vulgare the grains are somewhat less irregular and less variable in form, that the lamellae are 

 visible in a less number of grains and fewer in number, and the slightly smaller size of the grains, 

 all of which differences are minor and may be incidental, there are no noticeable differences in the 

 gross histological characteristics. In the reactions, in this starch polarization is slightly higher, 

 the iodine reaction slightly lower, the temperature of gelatinization higher (1.1°), and the sen.sitivity 

 less to all of the chemical reagents. While the differences are not marked they are sufficient to 

 permit of a positive differentiation. 



GENUS SECALE. 



Secale cereale Linn., which is the only cultivated rye, is regarded by Hackel as originating from 

 S. montanum, a native of the region between the Black Sea and the Caspian. Two agricultural 

 forms of this species, Mammoth Winter rye and Spring rye, were studied as types. 



STARCH OF SECALE CEREALE VAR. (MAMMOTH WINTER). 

 (Plate 2, figs. U and 12. Chart 17.) 



Histological Characteristics. — Inform the grains are simple and generally isolated. Aggregates 

 are frequently observed which coasist usually either of numerous minute grains or of one large 

 grain with several very small ones adhering to it. There are, as in Triticum, two clas.sos of grains, 

 large and small, which represent different forms of starch. The conspicuous forms among the large 



