GENUS IXIA. 



761 



P I GV T P 

 S 



Qart No. 298. 



Gy s 



CI CA PA FC P S CI PA CA 

 "" ' ' ' ■ POPS 



The degree of polarization is fair, varying somewhat in different grains but not much in dif- 

 ferent aspects of the same grain. 



With selenite the quadrants are fairly well defined, generally regular in shape, and of unequal 

 size. The colors are pure. 



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

 violet; with 0.125 per cent solution they color rather lightly and the color deepens slowly. After 

 heating in water until the grains are completely gelatinized, the solution colors lightly and the 

 swollen grains very deeply on the addition of iodine. After boiling for 2 minutes the solution 

 colors deeply and the grain-residues fairly or not at all. The capsules color violet with an excess 

 of iodine. 



Staining Reactions. — -With gentian violet the grains begin to stain very lightly at once and in 

 30 minutes are only lightly stained. 



With snfranin the grains begin to stain at once and in 30 minutes are fairly stained. 



Temperature Reaction. — The temperature of gelatinization is 83° to 85° C, mean 84°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in all the grains in 20 

 seconds and is over in 8 minutes. The grains color violet and then a dark indigo-blue along the 

 lines which border the facets, and this darkened portion swells slightly. This process now pro- 

 ceeds about the margin of the grain and then inwards. 

 It progresses more rapidly into the interior of the grain 

 from the distal end. When the hilum is reached the 

 whole grain rapidly increases in size and all the starch 

 becomes of a dark indigo color. Later the swollen grains 

 are seen to consist of a round, light inner space sur- 

 rounded by a thick, dark border. The gelatinized grains 

 are not very large and retain much of their original 

 form. 



The reaction with chromic acid begins in 5 seconds 

 and is over in IJ/^ minutes. The grains become covered 

 with fine striae which radiate from the hilum. The hilum 

 rapidly increases in size, and the rest of the grain swells 

 until all the less resistant starch has been gelatinized 

 and the more resistant material is gathered at the mar- 

 gin in a fairly thick, striated band. This band becomes 

 thinner and transparent, and is finally dissolved at one 

 point, usually one of the corners of the facets. The 

 gelatinized starch flows out and is dissolved, followed 

 by solution of the rest of the capsule. 



The reaction with pyrogallic acid begins in 30 seconds and is over in 10 minutes. The 

 hilum enlarges and fine striae appear which radiate from the hilum in all directions throughout 

 the grain. The less resistant starch in the central part of the grain passes into a gelatinous con- 

 dition, and the grain swells. The more resistant starch forms a thick, striated, marginal band, 

 which becomes somewhat thinner and clearer and may be seen to be divided into a very thin 

 inner portion and a thick outer portion. The gelatinized grains are large, smooth, and retain 

 much of their original form. 



The reaction with ferric chloride begins in many grains in 30 seconds and is over in 8 minutes. 

 The grains begin to gelatinize, usually at the corners of the facets, where the starch protrudes in 

 the form of small, irregular projections. This process spreads over the entire distal end of the grains 

 and then upward and inward. When the hilum is reached the surrounding starch is converted into 

 a gelatinous mass and the whole grain swells The more resistant material is gathered at the sides 

 and proximal end, where it becomes gelatinized, leaving only a thin, transparent capsule continuous 

 with that formed at the distal end. The swollen grains are large, somewhat irregular at the distal 

 ends, and do not retain much of the original form. 



With Purdy's solution most grains show some reaction in 1}/^ minutes. In 5 minutes about 

 one-third, including many large grains, are nearly completely gelatinized. In 10 minutes about 

 half and in 30 minutes all are nearly completely gelatinized. This reagent produces the same changes, 

 as far as appearances go, as pyrogallic acid. 



Curve of Reaction-Intensities of Starch 

 of Ixia speciosa. 



