GENERA ORNITHOGALUM AND ERYTHRONIUM. 



561 



Chart No. 153. 



PC PS 



s 



certain differences relating to the shapes in general are also of interest. A comparison of the inter- 

 ference figures and purity of colors with selenite shows a corresponding grouping. In their reac- 

 tions, species differences are manifest, but there is not the grouping that has been pointed out. 

 0. umbellatum and 0. narbonense (pyramidale) correspond, on the whole, distinctly, and much closer 

 than any other couple. The range of the temperatures of gelatinization is particularly noticeable, 

 the lowest being 55.5° and the highest 66°, a difference of 10.5°. By means of the variations in the 

 reactions each starch can without difficulty be distinguished from the others. 



GENUS ERYTHRONIUM. 



This genus consists of about 10 species, only one of which is European, the others being 

 natives of Eastern and Western America. Erythroniums are popularly known as the dog-tooth 

 violet or adder's tongue, and they bear nodding, lily-like flowers. Starches from 5 sources, 

 divided into 2 groups, were examined: Group I, E. dens-canis Linn, and E. dens-cards var. grandi- 

 florum Hort., this group including the European species and one of its varieties; Group II, E. ameri- 

 canum Smith (E. av^ustatum Raf., and E. bracteatum Boott), E. grandiflorum Pursh (E. giganteum 

 Lindl.), E. citrinum Wats., and E. californicum Hort., representing three of the native American 

 species. E. americanmn is Eastern and the others are Western American. 



STARCH OF ERYTHRONIUM DENS-CANIS. (Plate 39, figs. 229 and 230. Chart 153.) 



Histological Characteristics. — In form the grains are simple. There are a few small doublets 

 and a few clumps. There are pressure facets on some small grains. The surface is usually regular, 

 and any irregularities may be observed chiefly as protuberances of the proximal end or sides, or 

 one side of rounded triangular forms may be either more 

 inclined or shorter than the other; or the distal margin 

 may be expanded in these triangular grains, and an in- 

 dentation appears a little to one side of the longitudinal 

 axis and extends towards the hilum. The conspicuous 

 forms are elliptical, ovoid, pyriform, and variations of the 

 rounded triangular forms in the direction of clam-shell 

 and oyster-shell shapes. In some of the triangular forms 

 the base or distal end is almost pointed and the sides 

 shortened so as to yield the flint arrow-head shape. The 

 broad forms are flattened, and when viewed on edge the 

 grains are flattened elliptical. 



The hilum is a refractive spot which is generally fis- 

 sured by a small, irregular, transverse cleft, from which 

 two short, curved fissures (resembling ox horns) fre- 

 quently proceed; or in other instances branched, root-like 

 fissures are located here. Two hila are occasionally found. 

 There is a range of eccentricity of the hilum from one-fifth 

 to one-fourth, usually one-fifth, of the longitudinal axis. 



The lamellce are fine and usually indistinct. They 

 form complete rings around the hilum, but assume the shape of the grain near the margin and 

 distal end, where they are not so fine but more distinct. 



The grains vary considerably in size. The small, elongated grains measure 8 by 6m in length 

 and breadth; the larger, elongated types 40 by 36/n in length and breadth; and the broader, large 

 forms 34 by 38yn in length and breadth. The common size is 26 by 20ix in length and breadth. 



Polariscopic Properties. — The figure is eccentric, except in a few of the smallest grains, quite 

 distinct, and fairly clear-cut. Its lines are rather thick and generally straight, but somewhat 

 expanded at the distal and proximal ends. Sometimes they are either bent or bisected. 



The degree of polarization is fair. It varies in different grains as well as in the same aspect 

 of a given grain. 



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

 size. The colors are fairly 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 does not deepen rapidly. After 



Curve of Reaction- Intensities of Starch of Elrytfaronium 

 dens-canis. 



