776 STARCHES OF MUSACB^. 



In other grains the hilum swells and the capsule is dissolved at the proximal end, allowing any 

 broken-down starch to escape. Solution of the rest of the grain follows slowly, the starch apparently 

 being first divided by fine fissures, then broken off and gelatinized, and in this form flowing out into 

 the reagent in which it is dissolved. Rarely concentric crescents separate serially from the distal 

 end, along the lines of the most prominent lamellae, and dissolve independently. 



The reaction with pyrogaUic add begins in a minute and is over in 45 minutes. The hilura and 

 lamellse are very distinct. The hilum begins to swell slowly at first, this accompanied by the ap- 

 pearance of two non-refractive lines, which extend out on each side towards the distal end of the 

 grain. As the hilum swells, these lines appear to open out and become broader. The next step is 

 the dissolution of the rest of the substance of the grain. No one part seens to be affected before 

 another, but all melt gradually into a finely granular mass, which later clears and becomes quite 

 homogeneous. As this change goes on, the entire grain swells and is converted into a large, sac- 

 culated, folded, and invaginated ovoid mass. 



Reaction with /erne chloride begins in a minute and is over in 6 minutes. The reaction starts at 

 the margin at one point or at two points, usually at two points opposite one another, and these 

 begin to gelatinize, accompanied with great protrusion, the process extending around the margin, 

 usually towards the proximal end first. The hilum swells out into a long, saccular projection, and 

 many points on the sxurounding margin likewise protrude. Finally, the rest of the margin is sim- 

 ilarly affected, so that the ungelatinized central portion is completely surrounded by a gelatinous 

 margin with long, irregular projections. This central part becomes divided into several portions 

 by fissures. These portions are separated quickly and dissolve independently of one another. The 

 gelatinized grains are very irregular in outline and often reduced to a large, shapeless, granular mass. 



With Purdy's soltUion the reaction begins at once and is over in 13^ minutes. The reaction is 

 80 quick that it is difiicult or impossible to distinguish clearly the separate steps. It appears to 

 begin usually by enormous swelling of the hilum, followed by rapid gelatinization and swelling of 

 other parts of the grain; or both ends of the grain may gelatinize and swell. The upper portion of 

 the central parts of the grain becomes divided into granules by fine, radial striaj which extend from 

 the now swollen hilum, and also by fissures which appear along the lines of the most prominent 

 lamellae. This ungelatinized portion quickly swells in every direction and a large, gelatinized grain 

 is formed. The gelatinized grains may exhibit a number of sacculations; or may be merely unfolded 

 and wrinkled; or may show a series of folds following the lines of the lamellae. Sometimes there is a 

 long, finger-Uke projection at the distal end. 



STARCH OF MUSA ENSETE. (Plate 80, figs. 475 and 476. Chart 323.) 



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

 of clumps and a few aggregates in the form of doublets. Rarely grains show two or three hila, which 

 appear to have one non-refractive lamella around each, but all inclosed by the outer common 

 lamellae. There are no pressure facets on the isolated grains. Many of the grains are very irregular 

 in outline, owing to depressions, rounded protuberances, and nipple-like processes. The conspicuous 

 forms are the mussel-shell-shaped, clam-shell and oyster-shell types; also elongated ovoid, elongated 

 oval, rounded triangular, elliptical, straight or bent spindle form, and various irregular forms. The 

 grains are flattened, and when seen on edge or end they are irregular ellipses or spindles, sometimes 

 somewhat pyriform. 



The hilum is a round or oval, not very distinct, usually non-refractive spot, eccentric about one- 

 sixth to one-fourth, usually one-sixth, of the longitudinal axis. There are sometimes 2 or 3 hila. Occar 

 sionally there may be either an arched fissure or an irregular, small cavity at the position of the hilum. 



The lamelke are quite distinct, and they are finer but not so distinct in the immediate vicinity 

 of the hilum. In some grains they are quite coarse at the distal margin, in others fine. There are 

 frequently 3 to 5 very coarse and distinct refractive lamellae. The lamellae in the elongated ovoid 

 forms may form complete rings about the hilum, but beyond this region they generally assume the 

 form of the outline of the grain and are more or less irregular throughout. They also vary in the 

 coarseness. In some of the larger projections of the grain separate systems of lamellae seem to have 

 been added after the formation of the main part of the grain. The number is about 48 to 54 on the 

 long slender forms, to 28 to 40 on the broad shell-shaped. 



The size of the small grains is 10 by 8ai in length and breadth; of the larger elongated grains 

 44 by 22/i, and of the broad, large grains 30 by 50/i. The common size of the elongated giains is 

 24 by 14m, and of the broad grains 26 by 30// in length and breadth. 



