GENUS MU8A. 



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Polariscopic Properties — The figure is lusiially very eccentric, fairly distinct, but not clear-cut. 

 Its lines are from moderately thin to broad, and may bo straight, but often bent, or bisected, or 

 distorted because of variations in their width. The figure is better defined when the grain is 

 on edge or end. 



The degree of polarization is fair, varying somewhat in different grains and sometimes much in 

 different parts of the same aspect of a grain. It is distinctly higher than in M. cavendishii (stalk), 

 and on the whole not so variable. 



With selenite the quadrants are not clearly defined, 

 are irregular in shape, and unequal in size. The colors 

 are not pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solu- 

 tion the grains color a deep blue-violet; with 0.125 per cent 

 solution they color lightly and the color deepens fairly 

 rapidly. It is shghtly deeper than that of the grains of 

 M. cavendishii (stalk). After heating in water until all 

 the grains are completely gelatinized, the solution colors 

 deeply and the grains deeply on the addition of iodine. 

 After boiling for 2 minutes the solution colors very deeply 

 and the grain-residues lightly or not at all. The capsules 

 all color a red-violet with an excess of iodine. 



Staining Reactions. — ^With gentian violet the grains 

 begin to stain at once and in 30 minutes are fairly deeply 

 stained, some more than others. The stain is slightly 

 deeper than that of the grains of M. cavendishii (stalk). 



With safranin the grains begin to stain at once and 

 in 30 minutes are deeply stained, some more than others, 

 grains of M. cavendishii (stalk). 



Temperature Reaction. — The temperature of gelatinization is 62° to 64" C, mean 63°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins in most grains in 30 

 seconds, and all are darkened in 10 minutes. It is the same -qualitatively as that of the grains of 

 M. cavendishii (stalk). 



The reaction with chromic acid begins in most grains at once, and in the rest in a few seconds, 

 and is over in 50 seconds. As far as could be determined, it is the same qualitatively as that of the 

 grains of M. cavendishii (stalk). 



Reaction with pyrogallic acid begins in some grains in a few seconds and in all in 15 seconds. 

 Nearly all the grains are completely gelatinized, and the rest nearly completely gelatinized in 5 minutes; 

 and all are gelatinized in 15 minutes. The reaction is the same qualitatively as that of the grains 

 of M. cavendishii (stalk). 



The reaction with ferric chloride begins in a few grains in 20 seconds. Nearly all are gelatinized 

 in 4 minutes and all in 7 minutes. The reaction is the same quaUtatively as that of the grains of 

 M. cavendishii (stalk). 



The reaction with Purdy's solution begins in many grains in 15 seconds and in all in 30 seconds. 

 Nearly all are completely gelatinized in 2*^ minutes and all in 8 minutes. The reaction is quali- 

 tatively the same as that of the grains of M. cavendishii (stalk). 



Differentiation of Certain Starches of the Genus Musa. 



Curve of Reaction-Intensities of Starch of Musa ensete. 



The color is deeper than that of the 



Histological Characteristics. 

 Conspicuous Forms. 



M. cavendishii (stalk): Simple, no pressure facets, flat- 

 tened, margin irregular owing to depressions, 

 rounded projections, and nipple-like processes. 

 Mussel-shell-shaped and clam-shell-shaped. 



M. cavendishii (green fruit): Essentially the same as in 

 the foregoing, except that the mussel-ahell-shaped 

 is less prominent. 



M. sapientum: Essentially the same as in M. cavendishii 

 (stalk), except that the irregular ovoid is the most 

 prominent form. 



M. ensete: Essentially the same as in M. cavendishii 

 (stalk). 



HiSTOLOQicAL CHARACTERISTICS. — Continued. 

 Hilum — Form, Number, and Position. 



M. cavendishii (stalk): Form small, round, non-refrac- 

 tive, distinct spot. Not fissured ; no double or mul- 

 tiple hila noted. Position usually very eccentric. 



M. cavendishii (green fruit): Form the same as in the forego- 

 ing, except less distinct, and several grains with dou- 

 ble hila observed. Position usually very eccentric. 



M. sapientum: Form the same as in M. cavendishii 

 (stalk), except less distinct. Position usually very 

 eccentric. 



M. ensete: Form the same as in M. cavendishii (stalk), 

 except less distinct, and occasional double or triple 

 hila. Position usually very eccentric. 



