790 



STARCHES OF ZINGIBERACE.E. 



The reaction with Purdy's solution begins immediately and is over in 1 J^ minutes. The hilum 

 protrudes, the inner portion is converted rapidly into a gelatinous mass, and the grain swells. The 

 gelatinized grains so formed are smooth, as a rule, and retain some of the original form. 



Differentiation of Certain Starches of the Genus Hedijchium. 

 Histological Chabacteristics. 

 Conspicuous Forms. 

 H. coronarium: Usually simple, rare compounds, surface 

 may be irregular owing chiefly to nipple-like pro- 

 jections, flattened. Flattened ellipses with pointed 

 proximal end which commonly is curved. 

 H. gardnerianum: Essentially the same as in H. corona- 

 rium, but conspicuous forms belong to the clam- 

 shell type and flattened elhptical type. 



Hilum Form, Number, and Position. 



H 



coronarium: Form invisible in simple grains; small, 

 round, single, and indistinct in compound grains; 

 not fissured. Position extremely eccentric. 

 //. gardnerianum: Form the same as in H. coronarium. 

 Position extremely eccentric. 



LamellcB General Characleristics and Number. 



H. coronarium: Distinct, fine, regular arcs of circles. 58 



to 60. 

 H. gardnerianum: Fairly distinct, fine, regular arcs of 



circles. 30. 



Size. 



H. coronarium: From 8 to 62^, commonly 42m. 

 H. gardnerianum: From 5 to 42^, commonly 28^- 



PoLARiscoPic Properties. 



Figure. 



H. coronarium: Extremely eccentric, fairly distinct, not 



clear-cut. 

 H. gardnerianum: Extremely eccentric, not distinct or 



clear-cut. 



Degree of Polarization. 



H. coronarium: Low. 



H. gardnerianum: Very low, lower than in H. coronarium. 



Polarization irith Selenile Quadrants and Colors. 



H. coronarium: Quadrants not well defined, irregular in 

 shape, and unequal in size. Colors not pure. 



H. gardnerianum: Quadrants the same as in H. corona- 

 rium. Colors not pure. 



Iodine Reactions. 

 Intensity and Color. 

 H. coronarium: Fair; blue-violet. 



H. gardnerianum: Fair, less than in H. coronarium; blue- 

 violet. 



Staining Reactions. 

 With Gentian Violet. 

 H. coronarium: Deep. 

 H. gardnerianum: Deep, slightly less than mH. coronarium. 



With Safranin. 

 H. coronarium: Deep. 

 //. gardnerianum: Deep, but less than in H. coronarium. 



Temperature of Gelatinization. 



H. coronarium: 71.5 to 73.1 C, mean 72.3. 

 H. gardnerianum: 70.2 to 72.1 C, mean 71.15. 



Effects of Various Reagents. 



Reaction with Chloral Hydrate-Iodine. 



H. coronarium: Begins in most in 30 seconds; complete 



in 45 minutes. 

 H. gardnerianum: Begins in most in 15 to 30 seconds; 

 complete in 45 minutes. 



Reaction with Chromic Acid. 

 H. coronarium: Begins in 15 seconds; complete in 11 



minutes. 

 H. gardnerianum: Begins at once; complete in 5 minutes. 



Reaction with Pyrogallic Acid. 

 H. coronarium: Begins in a few in 90 seconds ; very slight 



reaction in 25 minutes. 

 H. gardnerianum: Begins in one-fifth in 60 seconds; about 



one-fifth are only partiaUygelatinized in 25 minutes. 



Reaction with Ferric Chloride. 



H. coronarium: General in 30 seconds; complete in 6 min- 

 utes. 



H. gardnerianum: General in 30 seconds; complete in 4 

 minutes. 



Reaction with Purdy's Solution. 

 H. coronarium: Begins at once; complete in 3 minutes. 

 H . gardnerianum: Begins at once; complete in l}i minutes. 



NOTES ON THE STARCHES OF HEDYCHIUM. 



The specimens of these starches are not very favorable for histological comparison, because 

 that of H. gardnerianum contains not only an abundance of eroded grains, but also much foreign 

 matter that could not be removed. The chief differences appear to be in the tendency of the latter 

 to a relative abundance of the clam-shell type, to a smaller size of grain, to less distinct lamellation, 

 and to a less tendency to the formation of a nipple-like proximal end. In their reactions they differ 

 BufEciently to be distinguished, H. gardnerianum having the lower degree of polarization, lower 

 reactivity with iodine and the anilines, lower temperature of gelatinization, and higher sensitivity 

 to chromic acid, ferric chloride, and Purdy's solution. 



GENUS CURCUMA. 



The genus Curcuma includes a few species of tuberous-rooted, herbaceous perennials that are 

 essentially tropical. They are to some extent cultivated as green-house plants, and some are of 

 more or less commercial importance. C. angusiifolia, C. leucorrhiza, and C. rubescens are the chief 

 sources of a form of East Indian arrowroot (see Marantacece, page 813) ; C. longa yields turmeric, 

 which is of importance especially as a dye-stuff and as a condiment; C. amada is the source of mango 



