GENUS ALSTRffiMBRIA. 



659 



Qart No. 224. 



I QV 

 S 



PS CI PA 

 ~ PC PS 



STARCH OF ALSTRCEMERIA LIGTU. (Plate 57, figs. 337 and 338. Chart 224.) 



Histological Characteristics. — In form the grains are commonly either compound or aggregates, 

 and made up of two, three, or more components. The lines of union of the component grains are 

 usually indistinct, but in some they are often shown in the form of one or more distinct fissures or 

 linear depressions which partly separate the grains from each other; sometimes there is merely a 

 more or less obscure marking. When simple grains can be made out, they are spherical to ovoid 

 in shape and rarely have pressure facets. Those with pressure facets are dome-shaped to hemi- 

 spherical. The compound grains are ovoid, and oval to elliptical. Occasionally a compound grain 

 will have small grains adhering to the siu-face. The components of a compound grain may be ar- 

 ranged linearly, or in two rows, or in irregular masses somewhat resembling a mulberry. 



The hilum is not distinct. It is a small, round, non-refractive spot. There are often double, 

 triple, or multiple hila. In the simple grains the hilum is usually centric or nearly centric and it 

 may be eccentric as much as two-fifths of the longitudinal axis. The hila in the compound grains 

 usually lie close to the median line or may be irregularlj' arranged. In the single grains the hilum 

 is situated in a space which sometimes is very distinctly outlined, giving the hilum the appearance 

 of being very large and distinct. It is sometimes marked by a fissure which usually is neither large 

 nor deep, and which may be single and placed generally in a transverse or longitudinal direction. 

 There may be two fissures crossing one another. 



The lamellce are not very distinct. When they can be fairly clearly seen they appear to be 

 rather coarse, concentric rings. There are sometimes small lamellae about each hilum. The out- 

 ermost rows of the compound grains encircle the grains, as a whole, following the outline of the 

 margin. The number of lamellae could not be estimated with exactness; from 4 to 9 were counted. 



The grains vary in size from 8 to 70/u, the common 

 size of the simple grains being about dOjx. The compound 

 grains vary from 40 to 70fi, the common size being 

 about 55ju. 



Polariscopic Properties. — The figure in the simple 

 grains is usually nearly centric. In the compounds and 

 aggregates it is eccentric and multiple. It is distinct but 

 not clear-cut. The lines are broad and widen near the mar- 

 gin. The multiple figures have a curious criss-cross form, 

 and double and multiple figures are extremely numerous. 



The degree of polarization is very high. The simple 

 grains and the doublets appear to have a somewhat higher 

 degree of polarization than the compounds of 3 or more 

 components. It varies in aggregates according to the 

 position of the grain. 



With selenite the quadrants are generally fairly well 

 defined, usually very irregular in shape, and unequal in 

 size, except in the simple spherical grains. The colors are 

 fairly pure. 



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

 tion the grains are colored a very deep blue-violet; with 0.125 per cent solution they color fairly 

 deeply and the color deepens rapidly. After heating in water until the grains are completely gelat- 

 inized, the solution is not colored, but the grains are colored very deeply, with iodine. After boil- 

 ing for 2 minutes the grains are much disintegrated and the residues react very lightly, but the 

 solution colors very deeply. With an excess of iodine the capsules become a violet color. 



Staining Reactions. — ^With gentian violet the grains begin to stain lightly in 30 seconds, and in 

 30 minutes are stained deeply and evenly. 



With safranin the reaction begins at once. Some grains are at first much more deeply stained 

 than others, but in 30 minutes they are deeply and evenly colored. 



Temperature Reaction. — The temperature of gelatinization is 58° to 59° C, mean 58.5°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in 45 seconds and is 

 over in 7 minutes. In all grains the hila become distinct as dark spots, but the lamellae are invis- 

 ible. The grains are darkened around the margin, and the lines of separation between the com- 



Curve of Reaction-Intensities of Starch of 

 Alstrcemeria ligtu. 



