792 STARCHES OP ZINQIBBRACEiB. 



around the margin and then advances rapidly towards the center from the distal margin until the 

 entire grain is gelatinized. The gelatinized grain is deeply colored, uniformly swollen, and retains the 

 general shape of the untreated grain. 



The reaction b^ns immediately with chromic add. A few grains are dissolved in 2 minutes, 

 more than half in 5 minutes, nearly all in 6 minutes, all but rare resistant grains in 8 minutes, and 

 all in 10 minutes. The hilum swells and the starch encircling it is quickly gelatinized. A large, 

 plume-like fissure or channel extends from this area, and the lamellae distal to the hilum become 

 sharply defined and striated. The capsule at the proximal end is soon ruptured and quickly dis- 

 solved, but gelatinization proceeds very gradually along the course of the branched fissure towards 

 the distal end accompanied by the appearance of numerous refractive granules, which remain for 

 a while embedded in the soluble starch; finally, the entire grain is dissolved. 



Reaction with pyrogallic acid begins in a few grains in 30 seconds. A small number are gelat- 

 inized in 3 minutes, practically all are partially gelatinized in 15 minutes, nearly all in 30 minutes, 

 with but shght signs of any progress from this time to the end of an hour. The hilum swells, the 

 lamellae towards the distal end become more distinct, and usually a delicate short fissure passes 

 from each side of the hilmn, but sometimes one longitudinal branched fissure extends towards the 

 distal end. Gelatinization begins aroimd the hilum and the starch at the proximal end quickly 

 becomes gelatinized, accompanied by a slight distension of the capsule. The reaction then proceeds 

 either between the two short, radiating fissures, or along the course of the single, branched fissure 

 until about one-half to three-fifths of the grain is gelatinized. In the grains with a large, single, 

 branched fissure the lamellae are cut down into a serrate lining of the capsule. The gelatinized grains 

 are swollen but retain the shape of the imtreated grain. 



The reaction with /cm'c chloride begins in 30 seconds. A few grains are gelatinized in 2 minutes, 

 more than half in 3 minutes, about four-fifths in 4 minutes, and all but the central part of a few 

 resistant grains in 5J^ minutes, in which gelatinization is complete in 10 minutes. A narrow border, 

 which more sharply defines the lamellae, forms around the grain. Gelatinization usually begins at 

 the proximal end, accompanied by rapid distension of the capsule, and quickly followed by swell- 

 ing at any prominent projections. Gelatinization proceeds for about the proximal third of the grain 

 towards the distal end, where the border of the more transparent lamellae has gradually broadened. 

 The starch at this margin now breaks into larger fragments, which quickly gelatinize. The lamellae 

 of the central part of the grain are the most resistant, but finally break into granules which are 

 broken down and the entire grain becomes gelatinized. The gelatinized grain is much swollen and 

 distorted. 



Reaction with Purdy's solution begins in a few grains in 30 seconds. A small number are gelat- 

 inized in 2 minutes, more than half in 3 minutes, nearly all in 5 minutes, and all but a few resistant 

 grains in 6 minutes, in which latter the reaction is complete in 10 minutes. The lamellae become 

 more distinct and striated, and the hilum swells. Gelatinization usually begins at the hilum, although 

 if there are very prominent protuberances swelling may start first and be more rapid in them. The 

 reaction usually proceeds towards the distal end, with a gradual breaking down of the lamellae 

 \mtil the entire grain is gelatinized. Sometimes one longitudinal, somewhat oblique fissure may 

 be observed proceeding from the hilum, from which occasionally large branches may form, so 

 that the lamellae are cut into a deep serrate lining of the capsule during gelatinization. The 

 gelatinized grains are swollen and somewhat distorted, but have a general resemblance to the 

 xmtreated grain. 



STARCH OF CURCUMA PETIOLATA. (Plate 82, figs. 489 and 490. Chart 331.) 



Histological Characteristics. — In form the grains are simple and are isolated, with the exception 

 of a few in clmnps. The grains are often irregular owing to the same causes as noted under C. longa. 

 The conspicuous forms are the same as in C. longa, but there are more irregular grains; the protuber- 

 ances are more prominent, those at the proximal end ranging from nipple-like to finger-shaped, 

 and those at the corners limiting the curved distal margin being longer and sometimes curved towards 

 the proximal end. 



The hilum is very indistinct, but rather more often visible than in C. longa, and always very 

 eccentric; thus the range varies with the length of the grain. It is usually eccentric from about 

 one-sixth to one-nineteenth of the longitudinal axis. 



