408 



STARCHES OF LEGUMINOS^. 



Staining Reactions. — The grains when viewed in masses show a slight tint of violet with gentian 

 violet and of red with safranin. After remaining in the solution for 30 minutes they are lightly 

 stained. The grains are more stained than those of Eugenie peas. 



Temperature Reaction. — The temperature of gelatinization is 69° to 71° C, mean 70°. 



Effects of Variotis Reagents. — With chloral hydrate-iodine the reaction begins at once. A few 

 grains are gelatinized in 2 minutes, about one-fourth in 15 minutes, and two-thirds in 30 minutes. 

 After remaining in the reagent for an hour very few if any more grains are gelatinized, but they have 

 the same golden-brown color already mentioned in connection with Eugenie peas. The reaction is 

 qualitatively the same as in the Large White Marrowfat peas. 



Reaction with chromic acid begins at once; a few grains are dissolved in 2 minutes, the majority 

 in 5K minutes, while an occasionally resistant grain may take 12 minutes to pass into solution. The 

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



Reaction with pyrogallic acid begins at once and a few grains are gelatinized in 50 seconds; 

 most are gelatinized in 2% minutes, and practically all in 4 minutes. The reaction is qualitatively 

 the same as in the Large White Marrowfat peas. 



With ferric chloride the grains begin to react in 30 seconds, the lamellae becoming very distinct. 

 A few are gelatinized in 15 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 some of the grains begin to react in about 30 seconds. A few are gelatin- 

 ized in 5 minutes, about one-tenth in 30 minutes, and two-thirds in an hour. The reaction is quali- 

 tatively the same as in the Large White Marrowfat peas. 



STARCH OF PISUM SATIVUM VAR. (MAMMOTH GREY SEEDED). (Plate 9, figs. 53 and 54. Chart 49.) 



Histological Characteristics. — In fortn the grains are simple, and are isolated except a few aggre- 

 gates in the form of doublets. There are no pressure facets. The grains are usually somewhat 

 irregular in outline, owing generally to slight depressions. The conspicuous forms arc ovoid to 

 oval, elliptical, and reniform. There are also round and 

 nearly round, especially among the small grains, and some 

 incidental irregular forms. The grains are not so thick as 

 broad and correspond in general characters with those of 

 Vicia, Phaseohis, etc. 



The hilum is probably represented by a small mesial, 

 granular non-lamellated space when the grain is not fis- 

 sured. In the small round grains there is a small central 

 hilum. Many of the grains show very extensive Assuring, 

 usually in the form of a deep, ragged, longitudinal fissure. 



The lamella; are distinct, rather coarse, continuous 

 lines which follow the outline of the grain, usually not so 

 coarse or distinct near the margin as in other parts and 

 not so distinct as in Electric Extra Early. There are 7 to 

 10 on the larger grains. 



The grains vary in size from the smaller, which are 

 4 by 4fi, to the larger, which are 40 by 28/* in length and 

 breadth. The common size is 29 by 22/1 in length and 

 breadth. 



Polariscopic Properties. — The figure is centric or 

 slightly eccentric, usually distinct, but not clear-cut; it is often impossible to determine the exact 

 characteristics of the figure, owing to interference of the fissures; in grains not fissured it generally 

 appears as a broad line along the longitudinal axis of the grains that is bisected at each end. 



The degree of polarization is fair, ranging from low to fairly high, not varying much in different 

 a.spects of the same grain; sometimes lower at some points than others, and in many grains com- 

 pletely lacking in the central parts. It is higher than that in Eugenie peas. 



With selenite the quadrants are commonly fairly well defined, irregular in form, and unequal 

 in size. The colors are, as a rule, pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color a fairly deep violet, 

 some having a more reddish tint than others; with 0.125 per cent solution they color a light violet 



PS CI PA ( 

 ~ PC PS 



Curve of Reaction-Intensities of Starch of Pisum sativum 

 var. (Mammoth Grey Seeded). 



