610 



STARCHES OF LILIACB^. 



CA PA FC P S CI PA CA 

 PCP3 



STARCH OF LACHENALIA PENDULA. (Plate 49, figs. 291 and 292. Chart 184.) 



Histological Characteristics. — In form the grains are simple, with the exception of a few com- 

 pounds consisting of two or more components. A few small aggregates of the smaller grains occur, 

 with a great tendency to form clumps. The grains often present well-marked irregularities of the 

 surfaces, such as large, nipple-like processes, or somewhat angular and rounded elevations, or slight 

 depressions. Many grains have a flattened area at the distal end, and in some cases a narrow and 

 shallow depression, which affects the form of some of the nearby lamellse. The conspicuous form is 

 the oval, which may be modified in various ways; for instance, by having commonly a rounded or 

 flattened distal end, which has a cup-like depression, or by being long and slender or short and broad, 

 or with a pointed or knob-like or much-bent distal end. There are also among the conspicuous grains 

 round, ovoid, and pyriform. Among the smaller grains there are round and nearly round, pyriform, 

 and oval forms. Any of these forms may be distorted by the irregularities of the surface, as above 

 noted. When seen on end they appear round. 



The hilum is usually very distinct. It is eccentric about one-fifth of the longitudinal axis of 

 the grain and usually in or near the median line. Double or triple hila may be arranged somewhat 

 irregularly. The hilum is generally a relatively large, round, non-refractive spot, but may appear 

 ellipsoidal or lenticular, or as an irregular cavity communicating with the interior. It is rarely 

 fissured, and if so the fissure is narrow, shallow, straight, clean-cut, transverse, or diagonal; or an 

 irregular stellate arrangement. The multiple hila may or may not be separated by small fissures. 

 The hilum is usually in the larger end of the grain. 



The lamellce are very distinct, fairly coarse, continu- Chart No. 184. 



ous rings, but often with variations caused by indenta- 

 tions or other irregularities of the surface of the grain. 

 They are usually coarser and more distinct near the 

 margin. There are 12 to 14 on the medium-sized grains. 



The grains vary in size from 5 to 36iU. The common 

 size is 20(1. 



Polariscopic Properties. — The^wre is eccentric, clear- 

 cut, distinct, and regular. Its lines are somewhat broad- 

 ened at the margin; one is sometimes bisected, but they 

 are usually straight. They intersect at right angles and 

 thus form a cross. 



The degree of polarization is fair. It is variable, being 

 higher in some grains than in others, and varies also ac- 

 cording to the aspect of the grain. 



With selenite the quadrants are, as a rule, well de- 

 fined, regular in shape, and somewhat unequal in size. 

 The colors are fairly pure. 



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

 tion the grains are colored deeply a blue-violet at once; with 0.125 per cent solution they color 

 hghtly, but the color deepens rapidly. After heating until the grains are completely gelatinized, the 

 solution is colored lightly and the grains very deeply on the addition of iodine. After boiling for 2 

 minutes, the solution is colored much deeper, but the grain-residues much less deeply. The cap- 

 sules are colored a pinkish-violet with a slight excess of iodine. The proximal part of the capsule 

 may contain blue-reacting starch, and the capsule is much distorted, folded, and crumpled. 



Staining Reactions. — With gentian violet and with safranin the grains stain at once lightly and 

 after 30 minutes they are fairly stained. 



Temperature Reaction. — The temperature of gelatinization is 60.1° to 60.7° C, mean 60.4°. 



Effects of Various Reagents. — With chloral hydrate-iodine the reaction begins in many grains in 

 a minute and all are completely gelatinized in 30 minutes. The hilum often becomes prominent, 

 the lamellse do not. The distal end is darkened, and the process spreads over the whole grain evenly 

 and without much swelling until the entire grain is affected, after which there may be slight swell- 

 ing. The swollen grains are not very large; they retain much of the original form and are uniformly 

 dark in all parts. 



Reaction with chromic acid begins in 15 seconds in the larger grains, most of which are dissolved 

 in 2J^ minutes; all the smaller are diaaolved in 5 minutes. The hilum is prominent and the lamelise 



Curve of Reaction-Intensities of Starch of 

 Lachenalia pendula. 



