454 



STARCHES OF AROIDE^. 



Differentiation of Certain Starches of the Genus Richardia. 



Histological Charactekistics. 



Conspicuous Forms. 



R. cllioliana: Simple, usually isolated and with pressure 

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

 angular, ovoid, spherical. 



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



R. albo-tnacidata: Essentially the same as in R. ellioliana. 



HUum Form, Number, and Position. 



R. ellioliana: Form small, fairly 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. ellioliana. Position centric 

 or slightly eccentric. 



R. albo-maculala: Form same as in R. africana. Position 

 centric or slightly eccentric. 



Lamellce General Characlerislics and Number. 



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

 do not follow the outline of the grain. Number not 

 determined. 



R. africana: Not visible. 



R. albo-maculala: Not visible. 



Size. 



R. ellioliana: From 1.4 to 18m, usually 12^. 



R. africana: From 1 to lOp, usually 6^. 



R. albo-maculala: From 1 to ICm, usually 8^. 



PoLARisconc Properties. 

 Figure. 



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

 lines nearly the same siz.e and distinctness through- 

 out, figure in form of a cross. 



R. africana: Practically nil. 



R. albo-maculala: Same as in R. ellioliana. 



Degree of Polarizalion. 



R. ellioliana: Fair. 

 R. africana: Almost nil. 



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

 iana. 



Polarization with Sclenile Quadrants and Colors. 



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

 equal or nearly etiual in size. Colors not quite 

 pure. 



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

 terminable. 



R. alhn-maculala: Quadrants the same as in R. ellioliana. 

 Coloi's not quite pure. 



Iodine Reactions. 



Intensity and Color. 



R. clliotiana: Deep; blue-violet. 



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

 R. albo-maculala: Deep, deeper than in R. ellioliana; blue- 

 violet. 



Staining Reactions. 



With Gentian Violet. 



R. cllioliana: Light. 



ft. africana: Light, less than in ft. cllioliana. 



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



With Safranin. 



ft. ellioliana: Very light. 



ft. africana: Very light, less than in ft. clliotiana. 



ft. albo-maculata: Very light, less than in ft. ellioliana. 



Temperature of Gelatinization. 



ft. ellioliana: 75 to 77 C, mean 76. 



ft. africana: 74 to 76 C, mean 75. 



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



Effects of Various Reagents. 

 Reaction uiilh Chloral Hydrale-Iodine. 



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

 utes. 



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

 utes. 



ft. albo-macidata: Begins in 30 seconds; complete in 10 

 minutes. 



Reaction with Chromic Acid. 



ft. ellioliana: Begins in 13^2 minutes; complete in 5 min- 

 utes. 



ft. africana: Begins in 1,^2 minutes; complete in 4 min- 

 utes. 



ft. albo-maculala: Begins in 2 minutes; complete in 10 

 minutes. 



Reaction with Pyrogallic Acid. 



ft. ellioliana: Begins in 2 minutes; about half are af- 

 fected, and one-fourth completely gelatinized in an 

 hour. 



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

 affected, and very few are completely gelatinized in 

 an hour. 



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

 show any signs of reaction. 



Reaction icilh Ferric Chloride. 



ft. clliotiana: Begins in 2 minutes; complete in 35 min- 

 utes. 



ft. africana: Begins in 2^2 minutes; complete in 40 min- 

 utes. 



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

 minutes. 



Reaction with Purdy's Solution. 



ft. ellioliana: Begins in 30 seconds, slight in a few grains; 



no further reaction. 

 ft. africana: Begins in 1 ^2 minutes, slight in 1 or 2 grains; 



no further reaction, 

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



grains; only a few grains are completely gelatinized 



in 13^ 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 extiihit diagnostic differences. In the reactions, R. ellioliana 

 and R. albo-macidala 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. 

 alho-maculata reaches 1.5 higher than in R. clliotiana. In tlie 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. 



