GENUS CURCUMA. 



791 



PS CI PA 

 PC PS 



ginger; C. zedoaria and C. aromalica furnish the East Indian drug known as zedoary, which is used 

 in medicine and in the preparation of incense, the latter species also yielding a turmeric-like article 

 of conamerce. Starches from two sources were examined: C. longa Linn, and C. petiolata Roxb. 



STARCH OF CURCUMA LONGA. (Plate 82, figs. 487 and 488. Chart 330.) 



Histological Characteristics. — In form the grains are simple, and are isolated with the exception 

 of a few in clumps. The grains are frequently irregular, owing chiefly to the following causes: to 

 small protuberances which are usually found at the proximal end or side nearby; to an indentation 

 at one side of the hilum; and to a slight deflexion at the proximal end and to small extensions of 

 the corners forming the ciu"ved margin of the distal end. The conspicuous forms are ovoid, often 

 with flattened sides and somewhat abruptly pointed proximal end; triangular with curved base; 

 pyriform, often with flattened sides; shield-shaped, somewhat mussel-shell-shaped, and imperfect 

 quadrilateral. The grains are much flattened and usually of narrow elliptical form when viewed on 

 edge. 



The hilum is very indistinct and occasionally may be observed as a round or lenticular spot, 

 very eccentric according to the length of the grain, usually eccentric one-eighth to one-fifteenth of 

 the longitudinal axis. 



The lamellm are usually not clearly demonstrable, especially near the hilum. When observed 

 they vary from rather fine to fairly coarse layers, which follow the outline of the distal margin and 

 are probably incomplete. On grains of large size 32 may 

 be counted, rarely 40. Chart No. 330. 



The grains vary in size; the smaller are 10 by 6/i; ^ > 

 the larger are 42 by 16yu in length and breadth. The vh > 

 common size is about 24 by ISfj. in length and breadth. 



Polariscopic Properties. — The figure is very eccentric 

 and usually indistinct where the lines intersect. Its lines ^ 

 are rather broad and frequently bent. 



The degree of polarization is fair, varying in the same 

 aspect of a given grain. At the proximal end polariza- 

 tion is absent or very low, but fair in from two-thirds to 

 four-fifths of grain. 



With selenite the quadrants are not clearly defined 

 and the one at the proximal end can rarely be distin- '" ' 

 guished. They are irregular in shape and unequal in 

 size. The colors are usually not quite pure. 



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

 tion the grains become a light, dull reddish-violet, some 

 deeper than others, the color deepening rapidly in some Curve of Reaction-inteiwitie. of starch of Curcuma long*, 

 grains and gradually in others. With 0.125 per cent 



solution the grains soon color a dull, light reddish-violet or gray (ashes-of-roses), deepening rap- 

 idly in most grains. After heating in water until all the grains are gelatinized, and then adding 

 iodine, the solution becomes a deep indigo-blue and the grains a fairly deep, rather dull blue, some 

 having a reddish tint. If the gelatinized grains are boiled for 2 minutes and then treated with 

 iodine, most of the grain-residues become a very light blue, with a few scattered ones of fairly 

 deep tint, and the solution colors more deeply. With an excess of iodine the grain-residues become 

 a deep, dull blue with reddish tint and the capsules a light to rather deep heliotrope color. 



Staining Reactions. — With gentian violet the grains do not color at once, but in 30 minutes 

 are fairly stained. The starch contained much yellow coloring matter (turmeric), which afl'ected the 

 tint of the aniline reaction. 



With safranin tlae grains do not color at once, but in 30 minutes are fairly stained. The yellow 

 coloration of the starch affects the tint of the reaction. 



Temperature Reaction. — The temperature of gelatinization is 82° to 83° C, mean 82.5°. 



Effects of Various Reagents. — With chloral hydrate-iodine reaction begins at once. A few grains 



are gelatinized in 10 seconds, nearly all in 20 seconds, and all in 30 seconds. The grains immediately 



color an old-rose and the hilum becomes more distinct. Gelatinization accompanied by a deep 



bluish coloration starts at the distal end or at any prominent projections. The deep color spreads 



52 



