774 STARCHES OF MUSACEiE. 



grain is affected; or the hilum may swell out at the same time the margin begins to darken; or the 

 hilum may not swell until the process is spreading over the margin, so that the inner portion of the 

 grain, which later becomes affected, may be entirely surrounded by a swollen irregular, gelatinous 

 ring. The gelatinized grains so formed are fairly large, often much sacculated, especially about 

 the hilum, which with two or three adjacent points swell out into a long, irregular, finger-like pro- 

 jection. At the distal end the grain shows concentric dark lines, more or less completely separated 

 by light spaces after the fashion of the arrangement of the lamellce. The grains may also be irregu- 

 lar and sacculated all around the margin. 



The reaction with chromic acid begins in 15 seconds and is over in 2}/2 minutes. The hilum 

 swells out very rapidly in the form of a long, finger-like projection which may or may not be dis- 

 solved at one point and open out. The rest of the graia is seen to be crossed by fine radial strise, 

 which become more and more distinct. The distal end of the grain is di\aded into a number of 

 concentric crescents, each consisting of not more than 2 lamellae. These crescents are usually sep- 

 arated serially, then break up into pieces which dissolve, and finally, the reaction reaches the upper 

 part of the giain, which has been divided into large granules by the radial strise and transverse 

 fissures following the Unes of the most prominent, non-refractive lamellae. These granules dissolve 

 one by one until the grain has disappeared. 



Reaction with pyrogallic acid begins in a minute and is over in 4.5 minutes. The hilum and 

 lamellae become more distinct. The hilum swells slightly and two non-refractive lines extend out on 

 each side, towards the distal end, and widen as the hilum swells. The grain now becomes divided 

 irregularly by many irregular fissures ruiuiing through the substance in all directions and also by 

 regularly fine, radial striae. The central part is now converted into a granular mass, the process 

 extending toward the distal end from the hilum. There is thus formed a large, gelatinized grain 

 that is much lobulated, folded, and crumpled, and which does not retain any of the original form 

 of the grain. 



The reaction with /erne chloride begins in 13^ minutes and is over in 4 minutes. The hilum is 

 prominent and the lamellae are not obscured. The reaction begins with gelatinization and swelling 

 at one or two points on the margin on one side, followed by the same process at one or two points 

 on the opposite side, or at either end. Other parts of the margin become clear and darker and the 

 process may proceed around it with great swelling and irregular protrusion. The inner portion 

 later becomes divided by fissures and the parts so formed separate quickly and gelatinize independ- 

 ently, accompanied by great and sudden expansion of the whole grain and subsequent invagination 

 and unfolding of one side. Or the process may proceed from the proximal towards the distal end, in 

 which case the grain is marked with folds which follow the lines of the principal lamellae. The prox- 

 imal end shows many long, narrow sacculations. A less common method of reaction is the swelling 

 and gelatinization of the hilum and distal end, the central portion being the last to be affected. 

 The gelatinized grains thus formed are essentially like those formed from the starch of the root. 



The reaction with Purdij's solution begins in 15 seconds and is over in 5 minutes. The hilum and 

 lamellae are rendered very prominent. Usuallj' the hilum and distal end begin to gelatinize coinci- 

 dently. The central portion is radially striated and is divided into rows of granules, corresponding to 

 the lamellte, by transverse fissures which follow the lines of the non-refractive lamellae. This is fol- 

 lowed by the rapid transformation of the granules into a gelatinous mass, accompanied by great swell- 

 ing of the whole grain. The grains so formed are very large and retain very little of the original form. 



STARCH OF MUSA SAPIENTUM OBTAINED FROM THE STALK. 

 (Plate 79, figs. 473 and 474. Chart 322.) 



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

 of a few clumps. There are no pressure facets. The outlines of the grains are usually quite irregular, 

 owing to rounded projections and nipple-like processes. The conspicuous forms are the irregularly 

 ovoid, clam-shell-shaped, oyster-shell-shaped, and mussel-shell-shaped, and oval to spindle-shaped. 

 These different forms are modified in various ways, so as to give a most varied assortment of shapes. 

 The grains are very flat, and when seen on edge or end usually appear to be of a narrow, spindle form. 

 Some of the irregularities appear to be due to additions after the grain was nearly fully formed. 



The hilum is a not very distinct, comparatively small, round, non-refractive spot. It is usually 

 situated very eccentrically, sometimes almost at the extreme proximal end, and in or to one side of the 

 median line. Some elongated, ellipsoidal hila occur, but neither multiple hila nor fissures are seen. 



