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STARCHES OF IRIDACEiE. 



The lamellce are very indistinct, but may be brought out by Purdy's solution; yet even with 

 this medium they were not very well defined. They appear as regular rings, which are rather 

 coarse, none being more prominent than the others. There are about 7 on a medium-sized grain. 



The grains vary in size from 3 to 26ju. The common size is 18/i. 



Polariscopic Properties. The figure is centric or slightly eccentric, distinct, but not, as a rule, 

 clear-cut. There is no marked bending or other distortion of the lines. Double or triple figures 

 are rare. 



The degree of polarization is fair, with little variation in different grains and in different aspects 

 of a given grain. It is probably very slightly higher than in Tritonia crocata. 



With selenite the quadrants are not sharply defined, but tend to be regular in shape and size. 

 The yellow is prone to be encroached upon by the red dividing lines. Apart from this the colors are 

 fairly pure. 



Iodine Reactions. ^With 0.25 per cent Lugol's solution the grains are colored fairly a blue- 

 violet, but more than those of T. crocata; with 0.125 per cent solution they color lightly, but slightly 

 more than those of T. crocata. After heating until the grains are completely gelatinized, the solu- 

 tion is colored faintly and the grains very deeply with 

 iodine. Capsules containing very little blue-reacting 

 starch have a violet color. After boiling for 2 minutes 

 the solution is more deeply colored, but the grain-residues 

 less deeply. Many capsules have a blue-violet color, while 

 others are blue with a reddish tinge. 



Staining Reactions. With gentian violet the grains 

 stain very lightly at once, but after 30 minutes the color 

 is very light. It is about the same as that of T. crocata. 



With safranin the grains stain lightly at once and 

 after 30 minutes are fairly stained, about the same as 

 T. crocata. This reaction is deeper than that with gen- 

 tian violet. 



Temperature Reaction. The temperature of gelatin- 

 ization is 81 to 82.5 C, mean 81.75. 



Effects of Various Reagents. With chloral hydrate- 

 iodine reaction occurs in many grains in a minute. All 

 are affected and some are completely gelatinized in 3 

 minutes and all in 30 minutes. The hilum is not very 

 distinct, but the lamellae are invisible. The grains are 



colored violet. The margin becomes dark and this process diffuses inwardly over the whole grain, 

 after which the grain swells. The gelatinized grains are not large and they retain much of the orig- 

 inal form of the grain. They are of an even dark color tlu-oughout. 



The reaction with chromic acid begins in most grains in 30 seconds and is practically over in 

 30 minutes. The hilum becomes distinct and then swells. The grain is divided by fine radial strise. 

 The inner part passes into a gelatinous mass. The marginal part forms a thick, finely striated 

 ring, which later is divided into a thin, transparent outer layer and a thicker inner layer. The 

 outer layer dissolves at the pro.ximal end and the two layers separate. The inner dissolves at one 

 point, followed by solution of other parts and complete disappearance of the grain. 



With pyrogallic acid there is some reaction in a few grains in 30 seconds and very slight gen- 

 eral reaction in 10 minutes. In 45 minutes some of those which began to react in 30 seconds are 

 only partially gelatinized; in others there is slight swelling. The reaction consists in the swelling 

 of the hilum, breaking down of the interior of the grain into a gelatinous mass, and the formation 

 of a marginal ring which grows clearer and narrower, but which never, except in those grains out- 

 side or near the edge of the cover-slip, becomes very thin or transparent. The gelatinized grains 

 are not large, and they retain much of the original form of the grains. 



A rapid reaction occurs with ferric chloride in a few grains in 30 seconds, the reaction is general 

 in 6 minutes, and reaches its limits in an hour, though the grains are not completely gelatinized. 

 The reaction consists in the solution of the inner part of the grain and the formation of an outer 

 ring, which grows thinner and more transparent as the grain continues to swell. The swollen 

 grains are large, usually smooth, and rounded, and rarely show any folds, wrinkles, or sacculations. 



Curve of Reaction-Intensities of Starch of Tritonia 

 crocata var. lilacina. 



