MUSA. 



729 



(3) a secondary set of lamellse whose longitudinal axis is 

 at an angle, usually of 90, with that of the primary set; 



(4) a greater development of one part of the distal end 

 than of the rest. The conspicuous form is the elliptical 

 which is usually rather slender and has a flattened distal 

 end, but which may be broad and have both ends rounded. 

 The additional forms are triangular with curved base 

 and rounded angles, ovoid, round and nearly round, pyri- 

 form, quadrilateral with rounded, corners, polygonal, 

 finger-shaped, and oyster-shell-shaped. There are many 

 more elongated forms than in M. arnoldiana, and hence 

 the grains are not so often flattened as in that species ; 

 but all the broader forms are flattened, and when viewed 

 on edge have an irregular rod-shape. Many of the grains 

 of this specimen have a crushed appearance and some of 

 them are eroded at the sides and distal margin. 



The hilum is as distinct as in M. arnoldiana, and is 

 a round or lenticular-shaped spot which in the majority 

 of the grains is not fissured. It is fissured somewhat 

 more often than in M. arnoldiana and the fissures have 

 the following forms : ( 1 ) A single, straight or curved line 

 which may be transverse or oblique; (2) an irregularly 

 stellate arrangement of fissures; (3) cruciate-, T- or 

 Y-shaped; (4) flying-bird shape. The hilum is eccentric 

 from 0.4 to 0.2, usually 0.24, of the longitudinal axis. 

 The degree of eccentricity is less than in some grains of 

 M. arnoldtana, but, on the whole, it is about the same. 



The lamella are often more distinct but not so fine as 

 those of M. arnoldiana. Near the hilum and in the proxi- 

 mal one-third of the grains they are regular, round or 

 oval, continuous rings. In the rest of the grain they have 

 in general the form of the contour of the grain, but are 

 often wavy and somewhat irregular in outline. Near the 

 distal end they are not so fine and become discontinuous. 

 There are, as in M. arnoldiana, one or more coarse re* 

 fractive lamellaa which divide the fine lamellae into bands 

 of varying breadth. The number counted on the larger 

 grains varies from 15 to 30, commonly 24, which is less 

 than in M. arnoldiana. 



In size the grains vary from the smaller which are 

 6 by 6/*, to the larger which are 50 by 34^, in length and 

 breadth. The common-sizes are 34 by 30/* and 32 by 

 22/*, which is slightly larger than in M. arnoldiana. 



POLABISCOPIO PBOPERTIES. 



The figure is more distinct and more often well de- 

 fined than in M. arnoldiana. The lines sometimes cross 

 at right angles or, as in M. arnoldiana, at acute angles of 

 widely varying size. They are not so often bent or 

 bisected as in M. arnoldiana. 



The degree of polarization varies from low to high 

 (value 45), slightly higher than in M. arnoldiana. There 

 are more grains in which it is moderate, and fewer in 

 which it is low, than in M . arnoldiana. There is also not so 

 much variation in a given aspect of an individual grain. 



With selenite the quadrants are more often clear-cut 

 and less unequal in size and irregular in shape than in 

 M. arnoldiana. The colors also are somewhat more often 

 pure than in that starch. 



IODINE REACTIONS. 



With 0.25 per cent Lugol's solution the grains all 



color a moderate blue-violet (value 50), somewhat less 



than in M. arnoldiana. The color deepens very rapidly 



until it is very deep and more bluish in tint. With 0.125 



23 



per cent Lugol's solution the grains all color a light to 

 moderate blue-violet, less than in M. arnoldiana, and less 

 in some grains than in others. The color deepens very 

 rapidly until it is very deep and more bluish. After 

 heating in water until all the grains are gelatinized and 

 then treating with a 2 per cent Lugol's solution, the 

 gelatinized grains all color a light to moderate indigo, 

 more than in M. arnoldiana; and the solution a deep 

 indigo, but less than in M . arnoldiana. If the prepara- 

 tion is boiled for 2 minutes and then treated with an 

 excess of a 2 per cent Lugol's solution, the grain-residues 

 color a light indigo, more than in M. arnoldiana; the 

 capsules a red or reddish violet as in this species and 

 the solution a very deep indigo as in this starch. 



ANILINE REACTIONS. 



With gentian violet the grains all color very lightly 

 at once, and in 30 minutes they are lightly to deeply 

 colored (value 45), less than in M. arnoldiana. More 

 of the grains are lightly and fewer deeply colored than 

 in M. arnoldiana. 



With safranin the grains all color very lightly at 

 once, and in 30 minutes they are lightly to deeply colored 

 (value 50), less than in M. arnoldiana. There are 

 more lightly colored and fewer deeply colored grains 

 than in M. arnoldiana. 



TEMPERATURE REACTIONS. 



The temperature of gelatinization of the majority 

 of the grains is 64 to 66.5 C., and of all 67.5 to 

 69 C., mean 68.4 C., or 3.4 higher than in M. 

 arnoldiana. 



EFFECTS OF VARIOUS REAGENTS. 



The reaction with chloral hydrate begins in 1 minute. 

 Complete gelatinization occurs in about 17 per cent of 

 the entire number of grains and 30 per cent of the total 

 starch in 5 minutes ; in about 52 per cent of the grains 

 and 69 per cent of the total starch in 15 minutes; in 

 about 65 per cent of the grains and 78 per cent of the 

 total starch in 30 minutes; in about 78 per cent of the 

 grains and 88 per cent of the total starch in 45 minutes ; 

 in about 88 per cent of the grains and 95 per cent of the 

 total starch in 60 minutes. (Chart D 553.) 



The hilum becomes distinct, attended by the forma- 

 tion of a bubble in a majority of the grains, many more 

 than in M. arnoldiana. The lamellae are at first not visi- 

 ble, but later become more distinct than in M. arnoldiana. 

 The grains, as in M. arnoldiana, become more refractive 

 after the addition of the reagent, and the first portion 

 of the grain to show this is a band of starch at the margin 

 which is broader at the distal end than elsewhere. Gela- 

 tinization begins at the distal margin and follows the 

 two methods described under M. arnoldiana. That seen 

 in a majority of the grains is the same as was found in a 

 minority of the elongated grains of M. arnoldiana; and 

 that noted in the comparatively few broad forms is the 

 same as that described for the majority of the grains of 

 M. arnoldiana. The gelatinized grains are more swollen, 

 do not have such thin capsules, and are not so much 

 distorted, as in M. arnoldiana. 



The reaction with chromic acid begins in a few 

 .grains in 15 seconds. Complete gelatinization occurs in 

 about 40 per cent of the entire number of grains and 

 70 per cent of the total starch in 5 minutes; in about 



