. Carnegie Institution of Washington publication. 444 STARCHES OF AROIDE^ I GV T P S Chart No. 78. GV 5 T CI CA PA FC P3 Cl_P_A CA. Curve of Reaction-Intensities of Starch of Arum italicum. The lamellce are indistinct; only some near the hilum are visible. They are coarse, regular, concentric rings, invisible in many grains. The grains vary in size from 2 to l(j/i. The common size is 10^. Polariscopic Properties.—The figure is usually clean-cut, in the form of a cross; generallj' very slightly eccentric. The lines are broad antl straight, tending to widen centrifugally. The degree of polarizat
. Carnegie Institution of Washington publication. 444 STARCHES OF AROIDE^ I GV T P S Chart No. 78. GV 5 T CI CA PA FC P3 Cl_P_A CA. Curve of Reaction-Intensities of Starch of Arum italicum. The lamellce are indistinct; only some near the hilum are visible. They are coarse, regular, concentric rings, invisible in many grains. The grains vary in size from 2 to l(j/i. The common size is 10^. Polariscopic Properties.—The figure is usually clean-cut, in the form of a cross; generallj' very slightly eccentric. The lines are broad antl straight, tending to widen centrifugally. The degree of polarization is fair, varying somewhat in different grains, being higher in the larger grains, and about the same in different aspects of the grains. It is higher than in A. palcestinum. With sclenile the quadrants are well defined, com- monly regular in shape, and, as a rule, about equal in size. The colors are fairly pure. Iodine Reactions.—With per cent Lugol's solu- tion the grains color deeplj' a blue-violet. The depth of color is about the same as that of the grains of Arum palcestinum. Using per cent solution the grains are colored lightly at first, the tint soon deepening, the reac- tion lieing the same as that oi A. pakvstinum. After heat- ing until all the grains are completely gelatinized, the solution is colored deeply, but the grains not very deeply, upon the addition of iodine. After boiling for 2 minutes the solution is colored more deeply, the grain-residues faintly. All of the capsules contain some blue-reacting starch, and it is therefore often difficult to demonstrate the reaction of the capsule, but capsules devoid of blue- reacting starch become of a violet color with an excess of iodine. Staining Reactions.—W\th gentian wofei the grains be- gin to stain lightly in 2 to 3 minutes, and after 30 min- utes they are not much more stained. The color is the same as that in the grains of A. palcestinum. With safranin the grains begin to stain very lightly
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