GENUS IXIA. 



763 



aart No. 300. 



IGV 

 S 



P3 CI PA I 

 ~ PC PS 



STARCH OF IXIA VAR. (EMMA). (Plate 78, figa. 463 and 464. Chart 300.) 



Histological Characteristics. — In form the grains are simple and isolated, with the exception of 

 a number of aggregates, usually in the form of doublets or triplets. Most of the isolated grains are 

 marked by one or more, generally one or two, pressure facets at the distal end. The surface is usually 

 quite smooth and regular. The conspicuous forms are the hemispherical with one to three pressure 

 facets at the base or distal end, and the spherical; also the ovoid and oval to elliptical. The smaller 

 grains are of similar forms. The doublets are oval to elliptical and the triplets roundly triangular. 

 The grains are of the same thickness aa breadth, and appear to be spherical when viewed on end. 



The hilum is a fairly distinct, comparatively large round spot, usually slightly eccentrically 

 situated and in or slightly to one side of the median line. There is sometimes a round cavity at the 

 hilum, and the hilum is seldom fissured. Lines, fissures, or depressions commonly mark the place 

 of union of the components of aggregates. 



The lamellce are rather indistinct, rather coarse, regular continuous rings which have the shape 

 of the grain, except those immediately surrounding the hilum. The number could not be accurately 

 determined, but there appeared to be about 5 or 6 on the larger grains. 



The grains vary in size; the smaller are 2fi, the larger 20 by 16m in length and breadth. The 

 common size is 14 by 12/x in length and breadth. 



Polariscopic Properties. — The figure is usually somewhat eccentric, distinct, and generally clear- 

 cut. In some grains commonly one, sometimes more, of 

 the lines are broad and not clearly outlined. 



The degree of polarization is fair, varying somewhat 

 in different grains and in the same aspect of a grain. It 

 is sometimes lower at the distal end near the facets than 

 elsewhere. It is slightly higher than that of the grains 

 of /. spedosa. 



With selenite the quadrants are fairly well defined, 

 generally regular in shape, and unequal in size. The 

 colors are pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solu- 

 tion the grains color a fairly deep blue-violet; with 0.125 

 per cent solution they color lightly and the color deepens 

 slowly. The color is less than that of the grains of /. 

 spedosa. After heating in water until the grains are com- 

 pletely 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 to not at all. The cap- 

 sules color violet with an excess of iodine. 



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

 30 minutes are lightly stained, but slightly less than the grains of /. spedosa. 



With safranin the grains begin to stain at once and in 30 minutes are fairly stained, but less 

 than those of /. spedosa. 



Temperature Reaction. — The temperature of gelatinization is 84° to 85° C, mean 84.5°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in most grains in 45 

 seconds. It is over in two-thirds of the grains in 5 minutes and nearly all are gelatinized in 20 min- 

 utes. The reaction is the same qualitatively as that of the grains of /. spedosa. 



Reaction with chromic acid begins in 15 seconds and is over in 2 minutes. It is the same qual- 

 itatively as that of the grains of I. spedosa. 



The reaction with pyrogallic add begins in a:ll the grains in a minute and is over in 17 minutes. 

 It is the same qualitatively as that of the grains of /. spedosa. 



Reaction with ferric chloride begins in most grains in 45 seconds and is over in 20 minutes. It 

 is the same qualitatively as that of the grains of /. spedosa. 



With Purdy's solution reaction begins in a few grains in 2 minutes, very few are partially 

 gelatinized in 5 minutes, and all are nearly completely gelatinized in 30 minutes. 



Curve of Reaction-Intensities of Starch of 

 Ixia var. (Emma). 



