832 STARCHES OF MARANTACE^. 



The degree of polarization is fair, varying in diiferent grains from high to low; it varies also in 

 different aspects of the same grain, being highest when the grain is viewed on end or edge, and in 

 different parts of the same aspect of a grain, being lower as a rule near the margin than near the 

 hilum. It is not so high as that of the grains of M. arundinacea var. (Commercial No. 1). 



With selenite the quadrants are fairly well defined, irregular in shape, and unequal in size. 

 The colors are not 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 lightly but the color deepens rapidly. The color is 

 not so deep as that of the grains of M. arundinacea var. (Commercial No. 1). After heating in water 

 until the grains are completely gelatinized, the solution colors fairly and the gelatinized grains very 

 deeply on the addition of iodine. After boiling for 2 minutes the solution colors deeply and the 

 grain-residues faintly or not at all. The capsules all color a red-violet with an excess of iodine and 

 many retain blue-reacting starch at the proximal end. 



Staining Reactions. With gentian violet the grains begin to stain in 2 minutes, and in 30 minutes 

 are fairly deeply stained, one as much as another. The color is not quite so deep as that of the 

 grains of M. arundinacea var. (Commercial No. 1). 



With safranin the grains begin to stain very lightly at once and in SOminutesthey are fairly deeply 

 stained. The color is not quite so deep as that of the grainsof M.. arundinacea var. (Commercial No. 1). 



Temperature Reaction. The temperature of gelatinization is 78 to 79 C, mean 78.5. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in most grains in 2 

 minutes, half are gelatinized in 9 minutes, and all in 20 minutes. The reaction is qualitatively 

 the same as that of M. arundinacea var. (Commercial No. 1). 



Reaction with chromic acid begins in 45 seconds and is over in 53-^ minutes. It is the same 

 qualitatively as that of M. arundinacea var. (Commercial No. 1). 



The reaction with pyrogallic acid begins in some grains in 30 seconds and in most of the rest in 

 1)4, minutes. About four-fifths of the grains are completely gelatinized in 8 minutes. The reaction 

 is the same qualitativelj'^ as that of the grains of M. arundinacea var. (Commercial No. 1). 



The reaction with /erne chloride begins in a minute and is over in 13 minutes. It is qualitatively 

 the same as that of M. arundinacea var. (Commercial No. 1). 



Reaction with Purdy's solution begins in some grains in 2 minutes and a few are partially or 

 completely gelatinized in 10 minutes. The reaction is qualitatively about the same as that of M. 

 arundinacea var. (Commercial No. 1). 



STARCH OF CALATHEA VITTATA. (Plate 90, figs. 537 and 538. Chart 352.) 



Histological Characteristics. Inform the grains are simple, except a few compounds and aggre- 

 gates, chiefly in the form of grains of two components. Pressure facets are rarely observed. There 

 are a few clumps of grains and also of foreign matter. The surface of the grains is usually some- 

 what irregular, owing to slight depressions and nipple-like projections. The conspicuous forms are 

 oval to ovoid and elliptical; some approach the clam-shell-shaped and mussel-shell-shaped. There 

 are also spherical or nearly spherical, rounded triangular, pointed elliptical, and rod-like. Some of 

 the rounded triangular forms are compound grains, usually doublets or triplets. When viewed 

 from the edge the ovoid to oval and elliptical forms are usually broadly lenticular or spindle-shaped. 

 The hilum is a fairly distinct round spot, usually centric or nearly centric, or sometimes eccen- 

 tric to about four-ninths to two-fifths, usually four-ninths. There may be 2 or more hila in the simple 

 grains and at times as many as 4 to 6. The hilum may be fissured by a single fissure or the fissm-a- 

 tion may be ragged and much branched. 



The lamella are distinct, coarse, quite regular, complete rings around the hilum. In many 

 angular and otherwise irregular forms they tend to assume the shape of the margin of the grain at 

 about the third or fourth conspicuous lamella from the hilum; and in the case of grains with double 

 or triple hila the first lamella around the hila may have the marginal shape. In the large grains 

 there are 10 to 14 lamellEe. 



The size of the smaller grains is 6 by 6/i, and of the larger 24 by 38ju in length and breadth. 

 The common size is 20 by 28ju in length and breadth. 



Polariscopic Properties. The figure is usually centric or slightly eccentric and not very clear- 

 cut, but regular. Its lines are rather thick and usually broaden as they proceed from center to mar- 

 gin. They are usually straight, but may be more or less bent, bisected, or otherwise distorted. 



