GENUS CALATHEA. 



The degree of polarization is rather high. It varies in the different grains and in the same 

 aspect of one grain. It is not so high as in M. arundinacea var. (Commercial No. 1). 



With selenite the quadrants are as a rule not sharply defined, quite irregular in shape, and 

 unequal in size. The colors are not pure. 



Iodine Reactions. — With 0.25 per cent Lugol's solution the grains color a fair blue-violet; with 

 0.125 per cent solution they color very lightly and the color deepens somewhat. It is lighter than that 

 of the grains of M. arundinacea var. (Commercial No. 1). After heating in water until the grains 

 are completely gelatinized, the solution colors lightly and the grains very deeply on the addition 

 of iodine. After boiling for 2 minutes both the solution and the grain-residues color fairly deeply. 

 The capsules all color violet with an excess of iodine. 



Staining Reactions. — With gentian violet and with 

 safranin the grains begin to stain at once and in 30 

 minutes they are fairly stained, some more than others. 

 The color is not so deep as that of M. arundinacea var. 

 (Commercial No. 1). 



Temperature Reaction. — The temperature of gelatin- 

 ization is 82.5° to 84° C, mean 83.25°. 



Effects of Various Reagents. — With chloral hydrate- 

 iodine reaction begins in many grains in 15 seconds, in 

 all in IJ^ minutes, and nearly all are gelatinized in 10 

 minutes. The reaction is the same qualitatively as that 

 of the grains of M. arundinacea var. (Commercial No. 1), 

 except that often the entire margin becomes gelatinous 

 first, then the central portion of the grain. 



With chromic add the reaction begins in most grains 

 in 15 seconds and in all in 30 seconds. It is complete in 

 5 minutes. It is the same qualitatively as that of the 

 grains of M. arundinacea var. (Commercial No. 1). 



Reaction with pyrogallic add begins in most grains 

 in 45 seconds. In 5 minutes one-half are partially and one-fifth of these completely gelatinized; 

 in 10 minutes three-fourths are partially or completely gelatinized; and in 20 minutes three-foiu-ths 

 are completely and the remaining one-fourth partially gelatinized. The reaction is the same quali- 

 tatively as that of the grains of M. arundinacea var. (Commercial No. 1). 



The reaction with ferric chloride begins in some grains in 45 seconds. In 30 minutes all are par- 

 tially gelatinized and about one-fifth are completely gelatinized. About half are completely gelat- 

 inized in an hour, four-fifths in 2 hours, and all in SJ^ hours. The reaction is the same qualitatively 

 as in M. arundinacea var. (Commercial No. 1). 



With Purdy's solution the reaction begins in some grains in 15 seconds and in a few more in IJ^ 

 minutes. In 8 minutes about one-half are reacting and one-fifth are completely gelatinized, and 

 half are fully gelatinized in 30 minutes. The reaction is the same qualitatively as in M. arundinacea 

 var. (Commercial No. 1). 



STARCH OF CALATHEA WIOTIANA. (Plate 90, figa. 539 and 540. Chart 353.) 



Histological Characteristics. — In form the grains are simple. There are a few small aggregates 

 and a few clumps. Pressure facets are occasionally noted. The surface of the grains is sometimes 

 slightly irregular, owing chiefly to nipple-like processes, slight depressions, and small, rounded 

 protuberances. The conspicuous forms are oval, clam-shell-shaped, mussel-shell-shaped, trian- 

 gular with rounded comers, elliptical, and flattened oblong; there are a few ovoid, spherical, elon- 

 gated dome-shaped, pointed elliptical, rounded quadrangular, and various irregular forms. When 

 viewed on edge many grains are rounded, wedge-shaped, or broadly lenticular. The proximal end 

 of the grain is usually narrower than the distal end. 



The hilum is a small round spot, usually eccentric about two-fifths to one-fifth, commonly 

 about two-fifths, of the longitudinal axis. Two hila are occasionally found. No fissuration was 

 observed except in a few grains which appeared to be undergoing disintegration. 



The lamellcB are distinct, coarse, fairly regular, complete rings around the hilum; towards the 

 distal end they tend to assume the shape of the grain and are probably incomplete. There is usually 



Curve of Reaction-Intensities of Starch of Calathaa 

 vittata. 



