384 



STARCHES OF I,EGUMINOS^. 



The reaction with Purdy's solution begins in nearly all the grains in a minute. A few are com- 

 pletelj" gelatiniz(>d and man}' partially gelatinized in 4 minutes, and two-thirds are ('omjiletely 

 gelatinized and one-thinl partially gelatinized in 25 minutes. The reaction is not fully completed 

 in an hour. It is the same qualitatively as that of the grains of V. saliva. 



STARCH OF VICIA GERARD!. (Plate 5, figs. 27 and 28. Chart 35.) 



Histological Characteristics. Inform the grains are simple and with the exception of a few are 

 isolated. The surface of the grains is frequently irregular, owing to elevations or indentations. The 

 conspicuous forms are bean-shaped, elongated irregular and regular oval, and ovoid. There are 

 also some round, triangular with rounded angles, irregularly heart-shaped, and broadly lenticular. 



The hilum may be observed in some of the round forms as a clear, slightly refractive, some- 

 what irregularlj' outlined spot which is centric or slightly eccentric. The position of the hilum in 

 the elongated forms is usually marked by a long, deep mesial fissure. This fissure may be clean- 

 cut, but is frequently ragged and generally much broadened and may have bisected ends. Lateral 

 fissures from it may extend almost to the margin of the grain. There is sometimes a central, granu- 

 lated non-lamellated area which may or may not he surrounded by a branched, wreath-like fissure. 



The lamella in the round forms are distinct, rather coarse, concentric rings ; and in the elongated 

 gTains they are continuous, coarse bands which tend for the most part to follow the contour of the 

 grain, and therefore show corresponding irregularities. The lamelliB are more distinct throughout 

 the grain, and more distinct in a greater majority of grains than in those of T'. saliva. They vary 

 from 5 to 12 in number. 



The grains vary in size from the smaller, which are 4 by 4,u, to the larger, which are 40 by 28/i 

 or 36 by 33;u in length and breadth. The common sizes are 28 by 22yu and 24 by 22,u in length 

 and breadth. 



Polariscopic Properties. The figure is centric in some of the grains, while in others it is slightly 

 eccentric. In the majority of the grains there is a large, dark, central space from which several 

 dark lines proceed. The lines of the figure in the small 

 simple gi-ains are rather thick and broaden towards 

 the margin. They may be straight or bisected. The 

 peculiarities of the figure are essentially the same as those 

 observed in V. saliva. 



The degree of polarization is high, as a rule. It is 

 absent from the central part of most of the grains, and 

 it sometimes varies in the same aspect of a grain. It is 

 higher when the grain is viewed from the edge or side. 

 It is about the same as or higher than in V. saliva, and 

 there is a larger number of grains in which it is high. 



With selenite the quadrants in some grains are well 

 defined throughout, while in others they are only dis- 

 tinct in the marginal parts of the grain. They are gener- 

 ally irregular in shape and unequal in size, and they may 

 be subdivided. The colors are usually pure. In some 

 grains the yellow is not quite pure. The colors, on the 

 whole, are slightly purer than in V. saliva. 



Iodine Reactions. With a 0.2.5 per cent Lugol's solu- 



PS CI PA CA 

 ^ PC PS 



Curve of Reaction-Intensities of Starch of Vici) 



MINUTES 

 gerardi. 



tion the grains all color a fairly deep violet; with a 0.125 



per cent solution they color a very light violet, which deepens gradually. They color about the same 

 as those of V. saliva. After heating in water until all the grains are completely gelatinized, the solu- 

 tion is changed to an indigo-blue and the grains to a dark-l)lue on the addition of iodine. After boil- 

 ing for 2 minutes the solution is colored very deeply, and some of the grain-residues a light blue and 

 others a l)right, rather light blue. With an excess of iodine the capsules stain a deep reddish-purple. 



Staining Reactions. With gentian violet the grains begin to stain in a minute and in 30 minutes 

 they are very lightly stained, a few deeper than others. The color is less than that of V. saliva. 



With safj-anin the grains begin to stain at once, anil in 30 minutes they are liglitly stained, a 

 few deeper than others. The color is less than that of V. saliva. 



Temperature Reaction. The temperature of gelatinization is 70 to 72 C, mean 71. 



