782 STARCHES OF ZINGIBERACEiE. 



deeply. A few grains are colored lightly and these have a violet-colored capsule. After boiling for 

 2 minutes, the solution is colored much more deeply, the grain-residues somewhat less, and most of 

 them have a violet-colored capsule. 



Staining Reactions. — With gentian violet the reaction begins immediately rather lightly, and 

 after 30 minutes the stain is fairly deep, deeper in some grains than in others; not so deep as the grains 

 of Z. officinale. 



With safranin staining begins immediately, but very faintly, and even after 30 minutes the 

 grains are lightly stained. There is slightly less coloration than in Z. officinale. 



Temperature Reaction. — The temperature of gelatinization is 81.7° to 82.8° C, mean 82.25°. 



Effects of Variovs Reagents. — With chloral hydrate-iodine some grains begin to react in a minute 

 and reaction is complete in 10 minutes. There is no further change within 6 hours. The hilum is 

 usually very distinct as a small, dark spot or bubble. The lamellae are visible. In the grains that 

 react, the distal end becomes very dark and swells. The hilum swells and protrudes from the top 

 of the grain as a small, rounded knob. From both ends the process of gelatinization extends over 

 the whole grain. Occasionally one of the ends is affected at first. The gelatinized grains are fairly 

 large and appear more or less homogeneous, though they may show some irregular, light cracks 

 or fissures in the central parts. 



Reaction with chromic acid begins in IJ^ minutes and is completed in 20 minutes. The hilum 

 becomes very distinct, but the lamellae are invisible. The central portions of the grain, extending 

 from the hilum to the distal end, become divided irregularly by many small fissures which gradually 

 widen until this part is transformed into an irregular, granular mass. The more resistant starch 

 at the margin forms a wall, which is especially thick at the sides of the grain and is usually quite 

 homogeneous, though it may be crossed irregularly by striae. The distal end is dissolved and the 

 granular starch po\irs out and is dissolved; the proximal end disappears; and, finally, the resistant 

 starch at the sides goes into solution. 



The reaction with pyrogallic add begins in a few grains in 2 minutes, but after 20 minutes a 

 few grains are partially gelatinized, and one or two are completely gelatinized. (The preparation 

 dried in about 45 minutes.) The hilum is always distinct and the lamellae are distinct throughout 

 the grain. The grain is altered into a gelatinous mass, beginning at the hilum. The more resistant 

 starch at the margin forms at first a homogeneous wall, through which are seen wedge-shaped 

 fissures. This wall or capsule gradually becomes clear and thinner, but apparently never entirely 

 disappears. The gelatinized grains so formed are large, irregular in outline, somewhat sacculated, 

 wrinkled, and involuted. 



The reaction with ferric chloride begins in 2}/^ minutes and is practically over in IJ^ hoiu-s. 

 (A few grains near the edge of the cover-slip apparently never become completely gelatinized.) 

 The hilum is prominent as a dark spot or bubble. The lamellae are invisible. In general, the re- 

 action appears to consist of the homogeneous dissolution and swelling of the entire grain, without 

 the formation in most cases of a definite capsule. In some grains the inner portion from the hilum 

 to the distal end is divided by irregular fissures, becomes granular, and forms a well-marked capsule, 

 which later disappears. The gelatinized grains formed by these processes, which are not very dif- 

 ferent fundamentally, are large, folded, crumpled, and shapeless. 



After 2 hours there is no reaction with Purdy's solution. 



STARCH OF ZINGIBER OFFICINALE VAR. JAMAICA No. 2. (Plate 80, figs. 479 and 480. Chart 326.) 



The starch was prepared from white rhizomes bought in the open market as Jamaica ginger. 



Histological Characteristics. — In form the grains are simple. No compound grains, aggregates, 

 or pressure facets were noted, but there are many clumps. The grains tend to be quite regular in 

 outUne, though some of them have a small, pointed projection at the top of the grain. The most 

 conspicuous grains are ovoid, somewhat narrowed at the proximal end; also short, elliptical forms, 

 oval, rounded triangular, rounded quadrangular, circular, and a few approaching the clam-shell 

 type. The grains are about one-fourth as thick as broad and usually appear as narrow, flattened, 

 elongated ellipses when seen on edge. 



The hilum is a medium-sized spot, fairly distinct, round and non-refractive. It is very eccen- 

 tric, but not at the very edge of the grain, as in Z. officinale, and it is usually in or near the median 

 line. There is often a non-refractive Hue on each side, extending out towards the distal end. It is 

 not fissured and there are no double or multiple hila. 



