458 STARCHES OF AROIDE^. 



intensity as that of the pith grains. After heating in water until all the grains are completely gelatin- 

 ized, the solution colors slightly and the grains very deeply on addition of iodine. After boiling 

 for 2 minutes the solution colors deeply and the grain-residues lightly. On adding an excess of iodine 

 the capsules color red-violet. 



Staining Reactions. With gentian violet the grains begin to stain at once and in 30 minutes 

 they are deeply stained. The color is lighter than that of the pith starch. 



With safranin the grains begin to stain at once and in 30 minutes they are fairly deeply stained, 

 one grain as much as another. The color is not so deep as that of the pith starch. 



Temperature Reaction. The temperature of gelatinization is 68.5 to 70.5 C, mean 69. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in some grains in 15 

 seconds and in all in a minute. It is over in almost all in 8 minutes and in all in 12 minutes. The 

 reaction is qualitatively the same as that of the pith grains. 



The reaction with chromic acid begins in 30 seconds and is over in 4 minutes. It is the same 

 qualitatively as that of the pith starch. 



The reaction ^vith pyrogallic acid begins in 15 to 30 seconds and is over in 3 minutes. It is 

 the same qualitatively as that of the pith starch. 



With ferric chloride the reaction begins in most grains in 30 seconds and is complete in 10 

 minutes. It is the same qualitatively as that of the pith-starch grains. 



Reaction with Purdy's solution begins in most grains in 45 seconds . In 7 minutes many grains 

 are partially gelatinized and the reaction is at an end in 30 minutes, when all the grains are partly 

 gelatinized. It is the same qualitatively as that of the pith starch. 



STARCH OF PITH OF DIEFFENBACHIA SEGUINE VAR. MACULATA. 

 (Plate 17, figs. 101 and 102. Chart 86.) 



Histological Characteristics. In form the grains are both simple and compound and show no 

 tendency to form aggregates. They are very irregular in shape and show many forms, including 

 round, ovoid, oval, pyriform, reniform, club-shaped, bottle-shaped, elongated elliptical with one end 

 squared, boot-shaped, T-shaped, boomerang-shaped, and various other forms with nipple-like or 

 knob-like projections. Transitional forms may be found between the elongated-elli]5tical and the 

 T- and boot-shaped. Occasionally a T-shaped grain may be seen with a secondary or smaller pro- 

 jection from the side of the grain. When viewed from the side, the round, ovoid, oval, T-shaped, 

 boot-shaped, and various irregularly shaped grains appear somewhat flattened; and from the end 

 they usually appear oval, ovoid, or round. They show a greater tendency to secondary deposits 

 and to be somewhat broader in tyjie than the starch of the cortex, and also to be larger. The tend- 

 ency to round, ovoid, and other short forms, and to freak forms such as the boot-shaped, etc., is 

 decidedly more marked in this species than in the other Dieffenbachia examined. 



The hilum is distinct and sometimes marked by a fissure, which may be divided at the 

 ends into several radial fissures, and be crossed by a fissure which also may be divided at the 

 ends. When not fissured, the hilum appears as a comparatively large, refractive spot. It is eccen- 

 tric from two-fifths to one-fifth of the longitudinal axis of the grains. It may be in the median 

 line or to one side. 



The lamellcB are distinct, continuous, alternate refractive and non-refractive rings, ellipses or 

 segments of rings and ellipses, which vary in size, spacing, and distinctness in the same grain and 

 in different grains. Except those near the hilum, they tend to follow the irregularities of the margin 

 and are often wavy even in grains having quite regular outlines. In the T- and boot-shaped and 

 some of the transitional forms there are two or three sets of lamella?, the secondary sets being formed 

 by plastids after the jirimary set has been completed. Occasionally in the T forms the lamellae 

 of the secondary and tertiary sets are coarser and more widely sjiaced than those of the primary, 

 both are finer than in D. seguine var. nohilis. The lamellae vary in number from 12 in the very small 

 grains to 66 in the large. The average for medium-sized grains is about 40. 



The grains vary in size from 10 to 70^, the common size being 40/i. They are ordinarily about 

 one-fourth as broad as long and two-thirds as thick as broad. 



Polariscopic Properties. The figure, excepting in the round, ovoid, and related forms, is very 

 eccentric and much distorted by irregularities of the grain. The lines are broad and ragged and 

 vary in width between the center of intersection and the margin of the grain. In the round, ovoid, 

 and related forms, and when the grains are seen on end, the figure may have the form of a cross. 



