GENUS COLCHICUM. 



623 



STARCHES OF COLCHICACE^. 



Class, Monocotyledones. Order, Liliales. Family, Colchicaceae. Genus 



represented, Colchicum. 



GENUS COLCHICUM. 



This genus is native chiefly of the Mediterranean region and Southern Europe, and includes 

 30 species of bulbous crocus-like plants which are popularly known as meadow saffron or autumn 

 crocus. The starch of C. parkinsoni Hook, was examined. 



PS CI PA C» 

 "" PCPS 



STARCH OF COLCHICUM PARKINSONI. (Plate 51, figs. 301 and 302. Chart 206.) 



Histological Characteristics. — In form the grains are simple, with the exception of a few com- 

 pounds consisting of two components. There are a number of aggregates consisting of from two 

 to five components, commonly two or three. The isolated grains are generally marked by one or 

 more pressure facets at the distal end, usually one or two. 

 There are a few clumps composed chiefly of small grains. 

 The surface of nearly all the grains is divisible into two 

 areas, one of which approaches the hemispherical, while 

 the other is planar and variable in accordance with the 

 size, number, and arrangement of the facets. The con- 

 spicuous forms are the dome-shaped to hemispherical, and 

 spherical; also irregular triangular, quadrangular, and 

 other angular forms arising through variations of the size, 

 number, and arrangement of the pressure facets. The 

 grains are not flattened, and therefore when seen on 

 end they appear roimd. 



The hiluni, if not fissured, is a not very distinct, 

 round, comparatively large spot, usually centric or nearly 

 centric, but it may be eccentric as much as two-fifths to 

 one-third of the longitudinal axis, and generally in the 

 median line. There are no multiple hila. The hilum is 

 usually fissured by from one or more fissures, which may 

 appear as a single line, a cross, or three lines radiating 

 from the center, or irregularly stellate. 



The lamellcB are not very distinct, rather coarse, regular circles or ellipses, which do not follow 

 the marginal outline unless located near the margin. There are 6 to 8 on the larger grains. 



The grains vary in size from 5 to 28^. The common size is 15/j. 



Polariscopic Properties. — The figure is usually centric or nearly centric, distinct, but not clear- 

 cut. It is generally placed so that two clear-cut lines run to the angles of the facets at the distal 

 end; but the other two lines, which extend to the proximal end, are broader and not so clear-cut. 

 The figure is regular or irregular, depending upon the shape of the grains. Double or triple figures 

 are oecasionallj- observed. 



The degree of polarization is high. It varies in different grains, but not much in different aspects 

 of the same grain. It is often higher at the distal than at the proximal end. 



With selenite the quadrants are well defined, usually regular in shape, but as a rule unequal 

 in size. The colors are usually pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color fairly a blue-violet; 

 with 0.125 per cent solution they color very lightly and the color does not deepen rapidly. After 

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

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

 deeply and the grain-residues lightly or not at all. The capsules color a violet with excess of iodine 

 and some of them retain blue-reacting starch at the proximal end. They are very much distorted, 

 cnmipled, and sacculated. 



Curve of Reacrion-In tensities of Starch of 

 Colchicum parkinsoni. 



