GENUS TRITONIA (MONTBRETIA). 



729 



Chart No. 281. 



GV S T g CA PA FC P S CI PA CA 



Some grains react immediately with Purdy's solution, the reaction is general in 4 minutes, and 

 about half are gelatinized in 35 minutes. In 2 hours practically all are completely gelatinized. The 

 reaction is, as usual, first a simple breaking down of the inner part into a gelatinous mass, followed 

 by much slower change in the marginal portion, which becomes a thin, transparent capsule. The 

 swollen grains are fairly large, rounded, and smooth. 



STARCH OF TRITONIA CROCATA VAR. ROSEA. (Plate 71, figa. 425 and 426. Chart 281.) 



Histological Characteristics. — In form the grains are mostly or solely simple and are isolated, 

 with the exception of numerous aggregates or compounds, chiefly in the form of doublets. Each 

 of the latter may be made up of components of equal to very unequal size, and many of them con- 

 sist of one large component with one that is small and having the appearance of being partially 

 embedded. There are some clumps, especially among the medium and small sizes, and there are 

 many grains with pressure facets, particularly of the hemispherical type, and some of the markings 

 are hexagonal like the honeycomb. The surface of the grains is rounded and tends to be quite regular. 

 The outline is usually modified in the doublets and triplets 

 by more or less marked depressions at the lines of union 

 of the component grains. The conspicuous forms of the 

 isolated grains are the spherical and transitional forms 

 between these and the ovoid. The doublets are mostly 

 ellipsoidal and ovoid, while the triplets are rounded tri- 

 angular. The grains are not flattened in any diameter and 

 therefore are of the same thickness as breadth. These 

 grains, in comparison with T. crocata, contain a relatively 

 large number of doublets and relatively few small grains, 

 and give the impression of being on the whole larger. 



The hilum is generally indistinct, but when the grains 

 are acted upon by Purdy's solution it appears as a small, 

 round spot which is centric or slightly eccentric. It is 

 rarely fissured. A single grain may show 2 or 3 hila 

 according to the number of components. Each hilum 

 may be surrounded by a separate set of lamellae, and in 

 others the hila are set close together in a common, non- 

 lamellated space, bordered by one very distinct lamella. 



The lamellcB are very indistinct unless they are inten- 

 sified by Purdy's solution or other reagent. They appear as regular, comparatively coarse, con- 

 tinuous rings. There are three sets in some of the doublets, one surrounding each hilum, and a 

 third surrounding the whole inner mass. There are about 8 on a large grain. 



The grains vary in size from 4 to 27;u. The common size is 17/i. 



Polariscopic Properties. — The figure is centric or slightly eccentric, but as a rule not clear-cut. 

 The figures may be single or double, according to the number of components. The lines are rather 

 broad, and there is no bending or other distortion of the figure. 



The degree of polarization is fair. There is not much variation in different grains or in differ- 

 ent aspects of the same grain. It is probably slightly higher than in T. crocata. 



With selenite the quadrants are not usually well defined, but tend to be regular in shape and 

 equal in size. The colors are fairly pure. 



Iodine Reactions. — -With 0.25 per cent Lugol's solution the grains are colored fairly and more 

 deeply than those of T. crocata, but with 0.125 per cent solution there was no difference. The 

 color is blue-violet. After heating until the grains are completely gelatinized, the solution is colored 

 fairly and the grains very deeply with iodine. After boiling for 2 minutes the solution is colored 

 much deeper, but the grain-residues somewhat lighter. In a few cases the grains exhibited a pinkish- 

 violet capsule when the color was not obscured by the intensity of the blue of the contained starch. 



Staining Reactions. — With gentian violet the grains stain inxmediately, but very sUghtly. After 

 30 minutes they are still very slightly stained, about the same as in T. crocata. 



With safranin the grains stain immediately but lightly. After 30 minutes they are faWy stained. 

 The color is about the same as that of the grains of T. crocata, but is deeper than with gentian violet. 



Temperature Reaction.— The temperature of gelatinization is 80° to 82° C, mean 81°. 



Curve of Reaction-Intensities of Starch of Tritonia 

 crocata var. rosea. 



