628 



STARCHES OF AMARYLLIDACB^. 



Curve of Reaction-Intensities of Starch of Hippeastrum 

 vittatum. 



and triangular and quadrangular and polygonal whose corners are very much rounded. There 

 are in addition spherical, lenticular, oval, elliptical, reniform, and some irregular forms. The 

 grains are rarely flattened, and therefore usually of the same thickness as width, and on end they 

 commonly appear spherical. Some of the large grains are from two-fifths to one-half as thick as broad. 



The hilum is a distinct, fairly large, round or rarely lenticular spot, which is eccentric sometimes 

 two-fifths, usually about one-third, of the longitudinal axis, and often to one side of the median line. 

 There are sometimes two or more hila in a single grain. 

 The hilum is often fissured, and the fissure usually is short, 

 narrow, and single, but ragged; or it may be deep and 

 broad, but never very long; or there may be cross-fissures. 



The lamelloe are distinct and fairly coarse. Near the 

 hilum they are continuous rings, often irregular in shape; 

 while at the margin several sets of discontinuous lamellae 

 frequently occur, whose longitudinal axes form angles of 

 varying degrees with the longitudinal axis of the grain. 

 The lamellae near the margin are, as a rule, coarser and 

 more distinct than those near the hiliun, and there is 

 usually one very distinct lamella which probably outlines 

 the margin of the grain before the secondary depositions. 

 There are 10 to 12 lamellae on the larger grains. 



The grains vary in size from 5 to 50//. The common 

 size is 24/x. 



Polariscopic Properties. — The figure is usually eccen- 

 tric, distinct, sometimes clear-cut, and irregular. The 

 lines are thick and may be thicker and not well defined in 

 some portions, especially as they near the margin. They 

 are often slightly bent and otherwise distorted, and may be placed at varying angles to one another. 

 A double figure is sometimes observed. 



The degree of polarization is high. It varies somewhat in different grains and in different 

 aspects of the same grain and sometimes in different parts of the same aspect of a grain. It is high- 

 est when the grain is \4ewed on end. 



With selenite the quadrants are not, as a rule, sharply defined, are irregular in shape, and unequal 

 in size. The colors are bright and usually pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color a very deep indigo, 

 and with 0.125 per cent solution they color fairly at once and the color deepens quickly. After 

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

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

 and the grain-residues very lightly, most of them not at all. With excess of iodine the capsules 

 color a red-violet. Many of the capsules are partially or wholly disintegrated. 



Staining Reactions. — With gentian violet the reaction begins very slightly at once and in 30 

 minutes the grains are fairly deeply stained, one as much as another. 



With safranin the reaction begins at once and in 30 minutes they are fairly deeply stained, 

 one grain as much as another. 



Temperature Reaction. — Temperature of gelatinization is 71° to 73° C, mean 72°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in some grains in 30 

 seconds, some grains gelatinizing almost at once. All are affected in 1 J^ minutes, about two-thirds 

 are gelatinized in 15 minutes, and all but very few grains in an hour. The reaction, except in 

 those grains which gelatinize very rapidly, begins at the margin of the distal end, which becomes 

 dark but does not swell. This color spreads over the surface of the grain, but remains deeper at 

 the distal end, and this deeper color advances slowly upward over the whole surface. When the 

 starch in the interior is affected there occurs slight swelling of the whole grain. The gelatinized 

 grains are not very large, are of a uniform dark color, and retain some of the original form of the grain. 



The reaction with chromic add begins in some grains in 15 seconds, in all in a minute, and is 

 over in 6 minutes. The reaction starts about the hilum, which swells, and the grain becomes cov- 

 ered by radial striae, which grow coarser as the grain increases in size. The less resistant starch 

 in the interior of the grain is changed into a gelatinous mass, while the more resistant exterior 



