838 



STARCHES OF MARANTACE^. 



Polariscopic Properties. — The figure is eccentric, distinct, fairly clear-cut, and regular. Its 

 lines are rather thin and sometimes broader and less clear-cut as they are nearer the margin, and 

 sometimes bent, and bisected. 



The degree of polarization is high. It does not vary greatly in different grains, but varies some- 

 what in different aspects of the same grain. It is highest when the grain is viewed on end. It is 

 slightly higher than that of M. arundinacea var. (Commercial No. 1). 



With selenite the quadrants are usually well defined, generally regular in shape, but unequal in 

 size. The colors are pure. 



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

 with 0.125 per cent solution they color fairly, some slightly more than others, and the color deepens 

 rapidly. It is much 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 fairly and the grains very 

 deeply on the addition of iodine. After boiling for 2 

 minutes the solution colors deeply and the grain-residues 

 lightly or not at all. The capsules are colored a red-violet 

 with an excess of iodine, and many of them retain blue- 

 reacting starch at their proximal end. 



Staining Reactions. — With gentian violet the grains 

 begin to stain at once very lightly, and in 30 minutes they 

 are only fairly stained, one grain as much as another. 

 The color is much lighter than that of the grains of M. 

 arundinacea var. (Commercial No. 1). 



With safranin the grains begin to stain at once 

 lightly, and in 30 minutes they are fairly stained, one 

 grain as much as another. The color is much lighter 

 than that of the grains of M. arundinacea var. (Com- 

 mercial No. 1). 



Temperature RecLction.— The temperature of gelatin- 

 ization is 82° to 83.5° C, mean 82. 75°. 



Effects of Various Reagents. — With chloral hydrate- 

 iodine reaction begins in most grains in l}/^ minutes. It is complete in half in 12 minutes, in prac- 

 tically all in 20 minutes. The reaction is qualitatively the same as that of the grains of M. arun- 

 dinacea var. (Commercial No. 1), except that the reaction begins at the distal end. 



The reaction with chromic acid begins in some grains in less than 30 seconds and in all in a 

 minute, and is over in 7 minutes. It is the same quaUtatively as that of the grains of M. arundinacea 

 var. (Commercial No. 1). 



With pyrogallic acid there is a very slight general reaction in 3 minutes and all the grains are 

 partially or completely gelatinized in 15 to 25 minutes. The reaction is the same qualitatively as 

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



The reaction with ferric chloride begins in some grains in 2 minutes. Most grains are gelatinized 

 in 15 minutes and all in 30 minutes. The reaction is the same qualitatively as that of the grains of 

 M. arundinacea var (Commercial No. 1). 



Reaction with Purdy's solution begins in many grains in IJ^ minutes. A few are completely 

 gelatinized and some others show a slight reaction, about two-fifths of the total number of grains 

 being affected, in 15 minutes. The reaction is qualitatively the same as in M. arundinacea var. 

 (Commercial No. 1). 



NOTES ON THE STARCHES OF MARANTACE^. (Charts 356 to 358.) 



Among the starches of MararUa two types of grains will be observed, one represented in the 

 starches of M. arundirmcea and its varieties and M. musaica; and the other type by M. massangeana 

 and M. Uuconeura. Among the Calathea starches two types appear to be distinguished, primarily by 

 the position of the hilum, in C. lietzei, C. wiotiana, and C. vandenheckei it being distinctly eccentric, 

 and in C. vittata nearly or quite centric. There are also distinct differences in the forms and other 

 characteristics of the grains. The starch of Stromanthe is histologically closer to Calathea than 

 to Maranta; and that of M. mv^aica might upon histological grounds be taken for a MararUa 



Curve of Reaction-Intensities of Starch of Stromanthe 

 aanguinea. 



