4S4 



STARCHES OF AROIDEiE. 



Differetitiation of Certain Starches of the Genus Richardia. 



Histological Characteristics. 

 Conspicuous Forms. 

 R. eUiotiana: Simple, usually isolated and with pressure 

 facets. Polygonal, dome-shaped, hemispherical, tri- 

 angular, ovoid, spherical. 

 R. africana: Essentially the same as in R. ellioliana. 

 R. cUbo-maculala: Essentially the same as in R. ellioliana. 



Hilum — Form, Number, and Position. 



R. eUiotiana: Form small, fairiy distinct, round spot; 

 rarely fissured. Position centric or slightly eccen- 

 tric. 



R. africana: Form usually invisible and not fissured, other- 

 wise the same as in R. eUiotiana. Position centric 

 or slightly eccentric. 



R. aUyo-maculaia: Yorm eamc as in R. africana. Position 

 centric or slightly eccentric. 



Lamellm — General Characteristics and Number. 



R. eUioliana: Not distinct, regular, concentric rings which 

 do not follow the outUne of the grain. Number not 

 determined. 



R. africana: Not visible. 



R. aU)o-maculala: Not visible. 



Size. 



R. eUiotiana: From 1.4 to 18/j, usually 12(u. 



R. africana: From 1 to lO/i, usually 6jj. 



R. albo-maculala: From 1 to 16/i, usually 8/j. 



PoLARiscopic Properties. 

 Figure. 



R. eUioliana: Centric or slightly eccentric, well-defined, 

 lines nearly the same size and distinctness through- 

 out, figure in form of a cross. 



R. africana: Practically nil. 



R. aUHHrnacuUUa: Same as in R. ellioliana. 



Degree of Polarization. 



R. eUiotiana: Fair. 

 R. africana: Almost nU. 



R. albo-maadata: Fair, probably lower than in R. elliol- 

 iana. 



Polarization with Selenile — Quadrants and Colors. 



R. eUiotiana: Quadrants well-defined, regular in shape, 

 equal or nearly equal in size. Colors not quite 

 pure. 



R. africana: Quadrants not determinable. Colors not de- 

 terminable. 



R. cdbo-maculata: Quadrants the same as in R. eUioliana. 

 Colors not quite pure. 



Iodine Reactions. 

 Intensity and Color. 

 R. eUioliana: Deep; blue-violet. 



R. africana: Deep, less than in R. ellioliana; blue-violet. 

 R. albo-mactdata: Deep, deeper than in R. eUioliana; blue- 

 violet. 



Staining Reactions. 



With Gentian Violet. 



R. eUioliana: Light. 



R. africana: Light, less than in R. ellioliana. 



R. albo-maculala: Light, the same as in R. ellioliana. 



With Safranin. 



R. dliotiana: Very light. 



R. africana: Very light, less than in R. ellioliana. 



R. albo-macxdata: Very light, less than in R. dliotiana. 



Temperature of Gelatinization. 



R. eUiotiana: 75 to 77° C, mean 76°. 



R. africana: 74 to 76° C, mean 75°. 



R. albo-maculala: 77 to 78° C, mean 77.5°. 



Effects of Various Reagents. 

 Reaction with Chloral Hydrate-Iodine. 



R. ellioliana: Begins in 30 seconds; complete in 20 min- 

 utes. 



R. africana: Begins in 45 seconds; complete in 5 min- 

 utes. 



R. albo-maculala: Begins in 30 seconds; complete in 10 

 minutes. 



Reaction with Chromic Acid. 



R. eUioliana: Begins in IJ.^ minutes; complete in 5 min- 

 utes. 



R. africana: Begins in IJ^ minutes; complete in 4 min- 

 utes. 



R. aUxMnaculata: Begins in 2 minutes; complete in 10 

 minutes. 



Reaction with PyrogaUic Acid. 



R. eUioliana: Begins in 2 minutes; about half are af- 

 fected, and one-fourth completely gelatinized in an 

 hour. 



R. africana: Begins in a few in 10 minutes; about half are 

 affected, and very few are completely gelatinized in 

 an hour. 



R. albo-maculala: Begins in 8 minutes; only a very few 

 show any signs of reaction. 



Reaction with Ferric Chloride. 



R. ellioliana: Begins in 2 minutes; complete in 35 min- 

 utes. 



R. africana: Begins in 214 minutes; complete in 40 min- 

 utes. 



R. albo-maculala: Begins in 2 minutes; complete in 75 

 minutes. 



Reaction with Purdy's Solution. 



R. eUiotiana: Begins in 30 seconds, slight in a few grains; 



no further reaction. 

 R. africana: Begins in 1 J/^ minutes, sUght in 1 or 2 grains; 



no further reaction. 

 R. albo-maculala: Begins in 5 minutes, slight in a few 



grains; only a few grains are completely gelatinized 



in 1 3^ hours. 



NOTES ON THE STARCHES OF RICHARDIA. 

 The starches of Richardia have the same general histological characteristics, and apart from 

 obvious differences in size do not exhibit diagnostic differences. In the reactions, R. eUiotiana 

 and R. aJbo-maculata differ little in the degree of polarization, whereas in R. africana the reaction 

 is very low. Little, and therefore unimportant, variations are recorded in the iodine, aniline, and 

 Purdy solution reactions. In the temperature of gelatinization, R. africana falls 1° lower, and R. 

 aWo-maculala reaches 1.5° higher than in R. eUiotiana. In the chloral hydrate-iodine, chromic acid, 

 pyrogallic acid, and ferric chloride reactions the differences are more or less marked, so that no 

 difficulty is experienced by means of the reaction-curves in reaching a diagnosis. 



