GENUS PISUM. 



409 



.111(1 the color deepens rather slowly. It is deeper than that of the grains of Eugenie pe.as. After 

 heating in water until all the grains arc completely gelatinized, the solution colors a blue-green 

 and the gelatinized grains a deep violet-blue on the addition of iodine. After boiling for 2 minutes, 

 the solution colors a deep indigo-blue and the grain-residues a reddish-blue. With an excess of 

 iodine the capsules stain a deep violet. 



Staining Reactions. When viewed in masses the grains are at once very lightly stained with 

 gentian violet, and show a tint of red with safranin. After remaining in the solution for 30 minutes 

 they are still very lightly stainetl. The color is slightly deeper than in Eugenie peas. 



Temperature Reaction. The temperature of gelatinization is 70 to 71 C, mean 70.5. 



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

 Swelling starts in a minute in a few grains and a few are gelatinized in 2 minutes. About half are 

 gelatinized in .30 minutes, with but little further change in an hour. Those which are not stained 

 a deep indigo-blue have cither a golden or a reddish-brown color. The reaction is qualitatively 

 the same as that in the Large White Marrowfat peas. 



The grains begin to react at once with chromic acid. A few are gelatinized in 45 seconds, 

 nearly all in 4 minutes, and all in 12 minutes. The reaction is qualitatively the same as in 

 the Large White Marrowfat peas. 



Reaction with pyi-ogallic acid begins at once. A few grains are gelatinized in a minute and all 

 in 3 minutes. The reaction is qualitatively the same as in the Large White Marrowfat peas. 



With ferric chloride the grains begin to react in a minute. A few are gelatinized in 6 minutes, 

 about one-tenth in 30 minutes, and about one-sixth in an hour. The reaction is qualitatively the 

 same as in the Large White Marrowfat peas. 



With Purdy's solution the grains begin to react in 30 seconds. A few are gelatinized in 3 minutes, 

 practicallj- all are affected in 10 minutes; about one-sixth are gelatinized in 30 minutes, and about 

 one-third in an hour. The reaction is qualitatively the same as in the Large White Marrowfat peas. 



STARCH OF PISUM SATIVUM VAR. (LARGE WHITE MARROWFAT). (Plate 10, figs. 55 and 56. Chart 50.) 



Histological Characteristics. In fmm the figures are simple and isolated. There are no pres- 

 sure facets. The outlines of the grains are usually somewhat irregular, owing to depressions. The 

 conspicuous grains are ovoid, oval, elliptical, and reniform; there are also round or nearly round, 

 triangular and quadrangular grains with rounded angles, 

 lenticular, and various irregular incidental forms. The 

 grains are net so thick as wide. They correspond in gen- 

 eral characteristics with the grains of Vicia and Phaseolus. 



There is a small central hilum in the small round 

 grains. If the grain is unfissured there is seen a central 

 non-lamellated, granular space which is probably to be 

 considered as the hilum. 



The lamellw appear as distinct, regular, rather coarse, 

 continuous lines, which have the form of the outline of 

 the grain. Those near the margin are less distinct than 

 those of other parts. They are not so distinct or coarse 

 as in Electric Extra Early. There are 10 to 12 on the 

 larger grains. 



The grains vary in size from small, which arc 6 by 

 6ju, to the larger elliptical, which are 50 by 28^ in length 

 and breadth, and the ovoid and oval, which are 42 by 

 28ju in lengtli and breadth. The common size is 34 by 

 2-iii in length and breadth. 



Polariscopic Properties. The figure is usually fairly 

 distinct, but sometimes the lines composing it are confused because of the fissures. In the unfissured 

 grains it commonly has the form of long, longitudinal, dark lines with liisected ends. The lines are 

 thick but fairly clear-cut, and not, as a rule, bent. 



The degree of polarization is fair to high, not varying much in different aspects of the same 

 grain, but often lower at some points than at others of the same aspect of a grain; it is much higher 

 than in Eugenie peas. 



Curve of Reaction-Intensities of Starch of Pisum sativum 

 var. (Large White Marrowfat). 



