422 STARCHES OP CVVVhlVEBJE, 



The degree of polarizalion is fair to quite high. It varies considerably in the different grains 

 and sometimes in the same aspect of a given grain. 



With selcnite the quadrants are usually well defined, irregular in shape, and unequal in size. 

 The colors are fairly bright to quite bright. The yellow is commonly proportionately brighter 

 than the blue, but more often varies in degree of brightness and purity, even in a given quadrant. 

 The colors are generally pure. 



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

 deepens fairly rapidly; with 0.125 per cent solution the grains color a very light blue-violet, which 

 also deepens fairly rapidly. AVhen the grains are heated in water until gelatinized, the solution 

 colors a light indigo-blue and the grains a dark blue on the addition of iodine. When the grains 

 are boiled for 2 minutes and then treated with iodine the solution is colored a deeper indigo-blue 

 and the grain-residues a fairly deep, bright blue. With an excess of iodine, the grain-residues become 

 deeper in color and sometimes have a slight reddish tint. The capsules usually color a light blue 

 with a slight reddish tint, or rarely an old-rose color. 



Staining Reactions. — With gentian violet the grains stain a very light violet immediately, and 

 the color deepens slightly in 30 minutes. Some grains stain more deeply than others. 



With safranin some of the grains show a very sUght trace of pink immediately, and the color 

 deepens slightly in 30 minutes. Considerable variation is found in the tint among the grains, some 

 not staining at all. 



Temperature Reaction. — The temperature of gelatinization is 60° to 61.5° C, mean 60.76°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in a few grains at once. 

 A few are gelatinized in 30 seconds, about one-half in a minute, practically all in 4 minutes, and all 

 in 7 minutes. The entire grain is immediately colored a light reddish-violet, which gradually deepens 

 to a light old-rose tint. Either a dark line or a ring appears at the region of the hilum, and in some 

 grains a bubble is formed at this point. In the ellipsoidal, bean-shaped, and related forms, swelling 

 and deepening of color usually begin at both ends and proceed towards the center, which is the 

 last to become gelatinized. If excrescences are found upon the grains, gelatinization begins at 

 these points, and when the entire grain is gelatinized these protuberances are lighter in tint. In 

 the grains in which a hilum is demonstrable, a clear area forms around the dark ring at the hilum 

 and also a delicate granular layer near the margin of the grain. In the pyriform grains, swell- 

 ing and deepening of color start at the distal end, and are soon followed by the same changes at 

 the proximal end, gelatinization then proceeding towards the center until the entire grain is in- 

 volved. The gelatinized grains are deeply colored and uniformly swollen, and retain somewhat 

 the shape of the untreated grain. The grains which have not become gelatinized have a golden- 

 brown tint. When the gelatinized grains remain in the solution for 3 hours they become a bright 

 indigo-blue. 



The reaction with chroinic acid begins immediately and all grains are dissolved in 25 seconds. 

 The grains swell rapidly, gelatinization is almost instantaneous, the capsules burst, and all parts are 

 dissolved. The reaction is so rapid that details of the process can not be determined. 



With pyrogallic add the grains begin to react immediately and all are gelatinized in 35 seconds. 

 Both hilum and lamellae become more distinct and fine strise appear upon the latter. Swelling 

 occurs at the cleft found in so many of the grains, and a bubble forms in it, which bubble after 

 expanding rapidly is expelled, usually accompanied by a temporary invagination of the capsule 

 at one point. From the large central cleft fine channels of gelatinization penetrate to all parts of 

 the grain until all is changed. If an eccentric hilum is demonstrable in a grain, this part swells, 

 and a longitudinal channel of gelatinization with delicate branches extends from it towards the 

 distal end and gelatinization proceeds as already described. Separate centers of gelatinization 

 form in the wart-like excrescences found in some grains, but finally merge with the body of the 

 grain. The gelatinized grain is much swollen and somewhat distorted, but the general shape of 

 the untreated grain is occasionally retained. 



Reaction with ferric chloride begins in many grains in a minute. A number are gelatinized in 

 5 minutes; about one-half in 10 minutes; a gradual change in 15 minutes; all but a few scattered 

 grains (one in several hundred) in 30 minutes; and all in an hour. The reaction begins at the margin, 

 which becomes less opaque and hence resembles a dark border encircling a lighter mass. Later, 

 either the hilum or both the hilum and the lamellae become more distinct. A bubble which slowly 

 expands and then collapses is often formed when either a very deep cleft or a cavity is present at 



