788 STARCHES OF ZINGIBERACE^. 



in 45 minutes. They begin to darken at the distal end and at the ends of any projections from the 

 surface. The hiium swells out as a little knob, and this becomes joined with other like swellings, 

 so that the whole margin becomes swollen and dark. The process usually extends along one side 

 more rapidly than the other. There is not often a very sharp line of demarcation between the 

 swollen and unswollen portions. The unswollen central part of the grain is quickly involved, but 

 the swelling as a whole is not great. The gelatinized grains when first formed are fairly large and 

 somewhat distorted, owing to the enlargement, twisting, and bending of the various projections 

 from the margin, and of a uniform dark color. After a little time the lower portion separates par- 

 tially from the rest of the grain and is seen to have a somewhat lamellated structure. 



With chromic acid the grains begin to react in 15 seconds, and reaction is over in 11 minutes. 

 The hilum protrudes from the top, and the grain shows on its surface long, irregiilar indentations 

 which later become irregular fissures. The lower end of the grain becomes fissured and granular, 

 and separates off bodily from the upper part, soon dissolving entirely; the remaining part divides 

 into rows of coarse granules in part by the irregular fissures before mentioned, and also by the other 

 fissures which extend transversely in the direction of the principal lamellae. The parts separated 

 by the latter fissures do not appear to separate serially from the grain, but the whole grain becomes 

 gradually thinner and more transparent until it disappears entirely. 



With pyrogallic acid a few grains begin to react in IJ^ minutes; there is practically no further 

 change after an hour, except in the grains outside the cover-slip. The hilum (when it can be 

 seen at all) and the lamellae become very prominent. The hila of grains outside the cover-slip 

 may swell somewhat, such exposed grains all becoming gelatinized in a very short time. In such 

 gi-ains the process appears to consist in the swelling of the hihnn, the invasion of the distal part of 

 the grain by many irregular fissures, and the gelatinization and swelling of this part. The gelatinized 

 grains are large and irregular in outline. The distal end shows a number of concentric folds arranged 

 somewhat like the lamellse. The grains under the cover-slip show no change after 25 minutes except 

 that they become clearer and more transparent; the lamellse more distinct; and the distal end of 

 the grain often partly separated from the rest, as if it were a cap adherent to the grain but not an 

 integral part of it. 



Reaction with ferric chloride is general in 30 seconds and complete in 6 minutes. The hilum 

 and one or two points nearby swell in long, finger-like projections. The rest of the grain, having 

 been divided Ijy irregular longitudinal striae and transverse fissures into granules, is converted into 

 a granular mass, with great swelling and much distortion. The distal end often separates, or par- 

 tially separates, from the main body and appears to gelatinize independently. The gelatinized 

 grains are very large, much distorted, folded, and bent. The lower portion shows lamella-like 

 rows of folds of the capsule. 



The reaction begins at once with Purdy's solution and is over in 3 minutes. The hilum and one 

 or two contigiious points protrude. The grain becomes divided by fine radiating striae and the entire 

 substance is changed into a gelatinous mass, inclosed by a thin, transparent capsule. The gelati- 

 nized grains are large and ovoid in shape, and the capsule or outer part is smooth. 



STARCH OF HEDYCHIUM GARDNERIANUM. (Plate 81, figs. 485 and 486. Chart 329.) 



Histological Characteristics. In form the grains are simple with the exception of rare compound 

 grains consisting of two components. There are no aggregates or pressure facets, and little ten- 

 dency to form clumps. The surface is rounded, with a marked tendency to irregularities of the 

 margin, due chiefly to nipple-like projections, especially from the proximal end. The grains are 

 quite varied in form, very much more than in H. cororiarium. The conspicuous forms belong 

 to the clam-shell type and the flattened, elliptical type with a pointed proximal end; also ovoid, 

 pyriform, triangular, spindle form, and various irregular forms. The grains arc much flattened, 

 and on an average are from one-fifth to one-fourth as thick as \vide. Wlien seen on edge they 

 are spindle-shaped. 



The hilum is generally not visible, due probably to its extreme eccentricity. In some double 

 grains a faint, very eccentric hilum may be discerned in each of the components, which is very 

 small and round, and situated in the median line. The hilum is never fissured. 



The lainella; are fairly distinct, regular, fine arcs of circles which are probably continuous and 

 follow closely the outline of the distal end. Those nearer the distal end are usually coarser and more 

 distinct than those near the hilum. There are about 30 lamellaj on the larger grains. 



