GENUS DIEFFENBACHIA. 467 



Staining Reactions. With gentian violet the grains are slightly stained in 3 minutes, and stain- 

 ing is at an end in 20 niiniitcs. The grains are deeply colored, about the same as with D. seguinc 

 var. nohilis, more than with D. scguine var. maculata. 



With snfranin the grains are slightly stained in a minute and after 30 minutes are deeply stained, 

 less deeply than those of D. seguirte var. nobilis. 



Temperature Reaction. The temperature of gelatinization is 69 to 70 C, mean 69.5. 



Effects of Various Reagents. With chloral hydrate-iodine the reaction begins in 2 minutes and 

 about three-fourths of the grains are completely gelatinized in 30 minutes. The hilum becomes 

 distinct as a black spot or bubble, but the lamella; do not change. The distal end begins to swell 

 and rarely there is swelling at both ends. Gelatinization proceeds towards the hilum, some portions 

 tending to swell more than others. In the T, boot, and other forms with two sets of lamella;, swelling 

 may begin at the distal end of both sets. In the elliptical grains when the hilum is reached it swells 

 and the grain becomes a gelatinous mass with the characteristic arrangement of alternate light and 

 dark bands, and of the annelid character referred to, with a rounded end inclosing the swollen hilum, 

 which may be obscured by a dark fissured mass, the distal end being flattened. The gelatinized 

 grains are modified in accordance with the form of the round grain. 



Reaction with chromic acid begins in a minute and is complete in 4 minutes. Neither hilum 

 nor lamellae are changed at first. Soon the hilum swells slightly, longitudinal fi.ssures extend in 

 from the distal end, and transverse fissures appear later and in conjunction with the longitudinal 

 lines break up the inner portion into granules which are arranged in rows corresponding to the 

 lamella". The margin becomes distinctly banded and finely striated. The distal end is usually the 

 first to dissolve, followed by solution of the inner granular portion, and then of other parts; or the 

 hilum may swell, the granules dissolve, and then the marginal part; or the proximal end may dis- 

 solve first, or both ends at once, but the latter is rare. The grains always become very clear before 

 dissolving, a condition not noted in any other of the Dieffenbachia starches. 



With pyrogallic acid reaction begins in 30 seconds and all the grains are swollen in 10 minutes. 

 Both hilum and lamellse become very distinct, the hilum appearing as a dark spot or bubble. Longi- 

 tudinal stria; appear at the distal end and extend upward and divide the inner portion, which later is 

 broken, in conjunction with transverse fissures, into irregular rows of granules. The margin becomes 

 finely striated and indistinctly banded. The hilum swells, the grain swelling chiefly longitudinally. 

 The granules in the inner part gradually gelatinize, the margin clears, and a completely gelatinized 

 grain is formed. Two conspicuous forms of gelatinized grains are thus produced, one being triangular, 

 the other oval. Both kinds are crumpled and lobulated with a smooth portion at the proximal end. 



The reaction with ferric chloride begins in 2 minutes and all the grains are gelatinized in 30 

 minutes. The hilum and lamellae are distinct. The margin becomes clearer and darker, causing 

 the inner portion to appear more opaque. Protrusion begins irregularly at the distal end of the grain, 

 the hilum swells, and longitudinal fissures extend from the distal end, which, in conjunction with 

 transverse fissures, breaks up the inner space into granules. The margin becomes finely striated 

 and shows distinct bands. The granules gradually disappear as the grain swells, and the margin 

 clears and becomes a thin and homogeneous capsule. Very rarely the reaction starts at both ends 

 of the grain. The gelatinized grains are large, irregular, crumpled, and lobulated; often they are 

 triangular, and occasionally ovoid or oval. 



Reaction with Purdy's solution begins in 2 minutes, but after Ij^ hours not more than one-fourth 

 of the grains show any signs of being affected. The hilum and lamelhe become very distinct. The 

 distal end swells, longitudinal fissures appear which extend upwards, the transverse fissures develop, 

 the crossed fissures causing an appearance of rows of granules. The margin becomes striated and 

 may show bands. Swelling proceeds from the distal end, and the granules disappear as the portion 

 of the grain in which the}' lie becomes gelatinized. The margin clears at last and a gelatinous mass 

 is formed. The gelatinized grains are large, crumpled, and lobulated, sometimes triangular, with 

 the swollen hilum at the apex. 



STARCH OF CORTEX OF DIEFFENBACHIA ILLUSTRIS. (Plate 19, figs. Ill and 112. Chart 91.) 



Histological Characteristics. Inform the grains are both simple and compound, and are almost 

 invariably isolated. The fundamental type is elliptical, usually with the proximal end narrower 

 than the distal end, the latter often being flattened. There is a marked tendency, as in the pith 

 starch, to a bending of the grain in its longitudinal axis, the curvature ranging from a slight 



