718 



STARCHES OF IRIDACE^. 



Curve of Reaction-Intensities of Starch of Gladiolus 

 cardinalis var. (Blushing Bride). 



The isolated grains vary in size from 3 to 26^. The common size is lOfi. The aggregates vary 

 in size from 7 to 37fi. The common size is 30/x. 



Polariscopic Properties. — The figure is centric or slightly eccentric, distinct, but not always 

 clear-cut. Its lines usually are broad, and become broader and less clear-cut near the margin. 

 They are usually straight and placed at equal distances from one another. The double or triple 

 figure is often very apparent in the case of aggregates and compounds of two or three components. 



The degree of polarization is high and does not vary much in different grains and only slightly 

 in difiFerent aspects of the same grain. It is distinctly higher than that of the grains of G. byzantinus. 



With selenite the quadrants are well defined, regu- 

 lar in shape, and usually equal in size. The colors are 

 pure. 



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

 tion the grains color a fairly deep violet; with 0.125 per 

 cent solution they color lightly, but the color deepens 

 quickly, and is slightly deeper than that of the grains 

 of G. byzantinus. After heating in water until the grains 

 are completely gelatinized, the solution colors fairly and 

 the grains deeply on the addition of iodine. After boil- 

 ing for 2 minutes both the solution and the grain-residues 

 color deeply. On the addition of an excess of iodine very 

 few capsules are colored a red-violet; others appear blue, 

 owing to the presence within of much blue-reacting 

 starch, which marks the color of the capsule. 



Staining Reactions. — With gentian violet the grains 

 begin to stain very lightly at once, and in 30 minutes 

 they are fairly stained. The stain is deeper than that 

 of G. byzantinus. 



With safranin the grains begin to stain lightly at once 

 and in 30 minutes they are fairly colored. The color is about the same as that of G. byzantinus. 



Temperature Reaction. — The temperature of gelatinization is 80° to 81° C, mean 80.5°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in many grains in IJ^ 

 minutes. Many of the smaller grains are gelatinized in 4 minutes. About one-third of the entire 

 number of grains are gelatinized in 11 minutes, two-thirds in 17 minutes, and three-fourths in 40 

 minutes. The reaction is qualitatively the same as that of the grains of G. byzantinus. 



The reaction with chromic acid begins in all the grains in 45 seconds and is over in 4 minutes. 

 It is the same qualitatively as that of the grains of G. byzantinus. 



Reaction with pyrogallic add begins in a minute, all the grains are partially gelatinized in 10 

 minutes, and almost all are completely gelatinized in 22 minutes. The reaction is the same quali- 

 tatively as that of the grains of G. byzantinus. 



The reaction with ferric chloride begins in some grains in a minute. About two-thirds are gelat- 

 inized in 15 minutes, almost all in 35 minutes, and all in 45 minutes. The reaction is the same 

 qualitatively as that of the grains of G. byzantinus. 



With Purdy's solution there is a slight reaction in many grains in a minute. About half of the 

 total number are somewhat swollen in 15 minutes and all are beginning to be gelatinized in 45 

 minutes. The reaction is the same qualitatively as that of the grains of G. byzantinus. 



STARCH OF GLADIOLUS FLORIBUNDUS. (Plate 69, figa. 413 and 414. Chart 275.) 



Histological Characteristics. — In form the grains are simple and isolated. Most of them are 

 marked at the distal end with one or more pressure facets and the grains tend somewhat to occur 

 in clumps, but no aggregates were noted. Small grains, generally globular or polygonal, are abun- 

 dant. The surface of the grains is regular but varied, owing to differences in size, number, and 

 arrangement of the facets. The conspicuous forms are spherical, almost spherical with one small 

 facet at the distal end, and somewhat quadrilateral with three basal facets and a rounded side 

 which is the proximal end; also dome-shaped, hemispherical with a pyramidal base or with a variable 

 number of facets, ovoid with one facet at the distal end, and various polygonal and other modifica- 

 tions. The grains are not flattened, and on end usually appear spherical. 



