800 



STARCHES OF CANNACEiB. 



STARCH OF CANNA MUSiEFOLIA. (Plate 83, figs. 495 and 496. Chart 337.) 



Histological Characteristics. — In form the grains are usually simple, with a few compound 

 grains consisting of two or three components. There are no aggregates or grains with pressure 

 facets. The grains are rounded but somewhat irregular in outiine, especially near the hilum. The 

 conspicuous form is the broad ovoid with the proximal end usually narrowed, and the clam-shell 

 type. They resemble quite closely the grains of C roscoeana. There are also reniform, pyriform, 

 triangular and quadrangular with rounded angles, and various irregular forms. Some of the longer 

 grains are bent about the longitudinal axis. The grains are distinctly flattened, being about one- 

 fourth as deep as wide. When seen on edge they may have a spindle form or be prismatic. 



The hUum appears as a small, round, very distinct, very eccentric spot, in or near the median 

 line. Occasionally the hilum is lenticular and more rarely it is centric. Multiple linearly arranged 

 hila occur rarely. Fissiu-ation is unconunon. 



The lameUw are very distinct coarse circles or regular arcs of circles which are probably con- 

 tinuous and follow closely the outline of the grain most distal to the hilum. As a rule, those nearest 

 the hilum are the coarsest and most distinct and vary much on different parts of the same grain. 

 On different grains they vary in distinctness and coarseness. The lamellae are more distinct and 

 sUghtly coarser than in C. tvarszewiczii. There are about 60 on the larger grains. 



The grains vary in size from 15 to 82;j. The common size is 55jtt. 



Polariscopic Properties. — The^wre is very eccentric, distinct, and usually clear-cut and regular. 

 The lines are broad, but usually of the same size and distinctness throughout their length. One or 

 two may be visible throughout their length; if one, it lies 

 in the longitudinal axis of the grain; if two, they cross the 

 grain diagonally from the hilum. 



The degree of polarization is very high, slightly higher 

 than that of the grains of C. warszewiczii. Polarization 

 colors are seen in many grains. It is highest when the 

 grain is on edge or end, and it does not vary greatly in 

 different grains. 



With selenite the quadrants are fairly well defined, 

 fairly regular in shape, and unequal in size. The colors 

 are pure. 



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

 tion the grains color very deeply a blue-violet; and with 

 0.125 per cent solution they color readily and the tint 

 deepens rapidly, the margins coloring more intensely 

 than the rest of the grain. The reaction is of the same 

 intensity as that of C. warszewiczii. After heating in 

 water until the grains are all completely gelatinized, the 

 solution colors a deep indigo and the grains a very light 

 indigo on the addition of iodine. After boiling for 2 



minutes the solution colors even more deeply and the grains not at all or very lightly, 

 slight excess of iodine the capsules color a red-violet. 



Staining Reactions. — With gentian violet the grains begin to stain at once and after 30 minutes 

 are deeply stained, some more than others. Most of them show deeply staining oval marks on their 

 surfaces. The shade is about the same as that of the grains of C. warszewiczii. 



With safranin the grains begin to stain at once and after 30 minutes are very deeply stained. 

 They are of about the same color as those of C. warszewiczii. 



Temperature Reaction. — The temperature of gelatinization is 70° to 71° C, mean 70.5°. 



Effects of Various Reagents. — ^With chloral hydrate-iodine reaction begins in a minute and is over 

 in half the grains in 7 minutes and in all in 20 minutes. It is qualitatively the same as that of C. 

 warszewiczii. 



Reaction with chromic acid begins in 30 seconds and is over in 33^ minutes. It is qualitatively 

 the same as that of the grains of C. warszewiczii. 



The reaction with pyrogallic acid begins in 13^ minutes. In 15 minutes a few grains are fully 

 gelatinized, while about one-fifth are partially gelatinous and the remainder merely show the begin- 

 ning of reaction. 



Curve of Reaction-Intensities of Starch of Canna 

 musiefoHa. 



With a 



