804 



STARCHES OF CANNACEiE. 



P I GV T P 

 S 



Chart No. 340. 



GV S T CI CA PA FC P S CI PA CA 



STARCH OF CANNA VAR. (PRESIDENT CARNOT). (Plate 84, figa. 501 and 502. Chart 340.) 



Histological Characteristics. In form the grains are simple, except rare compound grains con- 

 sisting of two components. There are no aggregates, clumps, or pressure facets. The surface shows 

 a marked tendency to irregularity, owing in part to a curving of the grains, but chiefly to rounded 

 protuberances and nipple-like projections. The conspicuous forms are flattened, irregular ovoid, 

 also broad ovoid, oval, pointed oval, flattened oval, irregularly quadrilateral, pyriform, bent or 

 straight lenticular, triangular with rounded angles, clam-shell type and mussel-shell type. The 

 grains are flattened and from one-fourth to one-half as thick as they are broad, and about one-half 

 to three-fourths or more as broad as long. 



The hilimi is sometimes invisible, owing to its extreme eccentricity; when not so eccentric, it 

 appears as a small, distinct, round or rarely elliptical spot, which may be located as far inward as 

 one-sixth to one-ninth of the longitudinal axis, and in or to one side of the median line. There are 

 occasionally 2 hila, and rarely more than 2 maj' be present 

 and arranged linearly. The hila may or may not be sepa- 

 rated from one another by a depression or a fine fissure, 

 but the hilum itself is never fissured. 



The lanwllce are very distinct, fine, regular or irregu- 

 lar circles, or arcs of circles which are probably continu- 

 ous. Except those immediately surrounding the hilum, 

 they tend to follow the outline of the distal end, but are 

 often wavy and otherwise irregular. They are frequently 

 arranged so that bands of varying numbers of fine lamellae 

 are grouped by scattered large, coarse lamellae. The 

 lamellae vary somewhat in size and distinctness in the 

 different grains and also in the same grain, being usually 

 not so fine but more distinct near the distal end. There 

 are sometimes two systems of lamellae. There are about 

 70 lamellae on the larger grains. 



The grains vary in size from 6 to 76fi. The com- 

 mon size is 50^1. 



Polariscopic Properties. The figure is very eccentric, 

 distinct, and sometimes clear-cut. One or two arms 

 may be seen throughout their length, and they are often broadened and not clearly outlined in 

 some part of their length, and they may be bent or otherwise much distorted or bisected. If one 

 long line is present it is usually located longitudinally; but if two are present they are usually oblique. 



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

 different aspects of the same grain, being highest when the grain is viewed on end, and occasionally 

 it varies in different parts of the same aspect of a grain. It is not so high as in the grains of C. 

 warszewiczii. 



With seleniie the quadrants may be well or poorly defined, and are fairly regular in shape and 

 unequal in size. The colors are usually not quite pure. 



Iodine Reactions. With 0.25 per cent Lugol's solution the grains color a deep bluish-violet, 

 some more than others; with 0.125 per cent solution they color fairly and the color deepens rapidly. 

 The color is deeper than that of the grains of C. warszewiczii. After heating in water until the grains 

 are completely gelatinized, the solution colors fairly and the grains fairly deeply on the addition of 

 iodine. After boiling for 2 minutes the solution colors more deeply and the grain-residues lightly 

 or not at all. The capsules all color a red-violet when an excess of iodine is added, and some of them 

 retain some blue-reacting starch at the proximal end. 



Staining Reactions. With gentian violet and with safranin the grains begin to stain at once 

 and in 30 minutes are deeply stained, some more than others, not so deeply as those of C. toarszewiczii. 



Temperature Reaction. The temperature of gelatinization is 64 to 66 C, mean 65. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in a minute and is over 

 in 9 minutes. It is the same qualitatively as that of the grains of C. warszewiczii, except that in 

 the beginning the grains are colored a much deeper violet. 



The reaction with chromic acid begins in 15 seconds and is over in 1^ minutes. It is the same 

 qualitatively as that of the grains of C. warszewiczii. 



Curve of Reaction-Intensities of Starch of Canna var. 

 (President Carnot). 



