714 



STAKCHES OF IKIDACEiB. 



Staining Reactions. — With gentian violet and with safranin the grains all begin to stain at once 

 and in 30 minutes they are lightly stained. The color is deeper than that of T. pavonia var. grandi- 

 fiora alba. 



Temperature Reaction. — The temperature of gelatinization is 59° to 61° C, mean 60°. 



Effects of Various Reagents. — ^With chloral hydrate-iodine the reaction begins in all in a minute 

 and is over in all in 7 minutes. It is the same quaUtatively as that of the grains of T. pavonia var. 

 grandiflora alba. 



With chromic acid the grains begin to react in a few seconds and reaction is over in 45 seconds. 

 It is the same quaUtatively as that of the grains of T. pavonia var. grandiflora alba. 



Reaction with pyrogallic add begins in a few seconds and is over in 50 seconds. It is the same 

 qualitatively as that of the grains of T. pavonia var. grandiflora alba. 



With ferric chloride a few grains begin to react in 45 seconds and reaction is over in all in 15 

 minutes. It is the same qualitatively as that of the grains of T. pavonia var. grandiflora alba. 



Reaction with Purdy's solution begins in some grains in 45 seconds. About four-fifths of the 

 grains are partially gelatinized in 8 minutes and all are completely gelatinized in 20 minutes. The 

 reaction is qualitatively the same as that of the grains of T. pavonia var. grandiflora alba. 



Differentiation of Certain Starches of the Genus Tigridia. 



Histological Chabacteristics. 

 Conspicuoits Forms. 



T. ■pavonia var. grandiflora alba: Usually simple, a few 

 small aggregates, no pressure facets; surface regu- 

 lar. Lima-bean-shaped, reniform, oval, and ovoid. 



T. pavonia var. conchiflora: Essentially the same as in 

 T. pavonia var. grandiflwa alba. 



HUum — Form, Number, and Position. 

 T. pavonia var. grandiflora alba: Form distinct large 

 round spot, or deeply and irregularly fissured. 

 Position eccentric 0.40 to 0.25, usually 0.33, of 

 longitudinal axis. 

 T. pavonia var. conchiflxtra: Form essentially the same 

 as in 7*. pavonia var. grandiflora alba. Position 

 eccentric from very slight to 0.33, usually 0.40, of 

 longitudinal axis. 



LameUce — General Characteristics and Number. 

 T. pavonia var. grandiflora alba: Not distinct; circles, 



ellipses or arcs of circles; fine or rather coarse; 



quite regular. Number not determined. 

 T. pavonia var. conchiflora: The same as in T pavonia 



var. grandiflora alba. Number not determined. 



Size. 



T. pavonia var. grandiflora alba: From 5 to 40/i, com- 

 monly 30m. 



T. pavonia var. conchiflora: From 8 to 34^1, commonly 

 24^. 



POLARISCOPIC PrOPEBTIES. 



Figure. 

 T. pavonia var. grandiflora alba: Eccentric, not distinct 



nor clear-cut, central part of grain dark. 

 T. pavonia var. conchiflora: The same as in T. pavonia 



var. grandiflora alba. 



Degree of Polarization. 



T. pavonia var. grandiflora alba: Very low to fair, very 

 variable. 



T. pavonia var. conchiflora: Very low to fair, very vari- 

 able; on the whole, lower than in T. pavonia var. 

 grandiflora alba. 



Polarizalion with Selenite — Quadrants and Colors. 



T. pavonia var. grandiflora alba: Quadrants poorly de- 

 fined, irregular in shape, unequal in size. Colors 

 not pure. 



T. pavonia var. conchiflora: Quadrants the same as in 

 T. jMvonia var. grandiflora alba. Colors not pure. 



Iodine Reactions. 

 Intensity and Color. 

 T. pavonia var. grandiflora alba: Fairly deep; indigo. 

 T. pavonia var. conchiflora: Fairly deep, deeper than in 

 T. pavonia var. grandiflora alba; indigo. 



Staining Reactions. 

 With Gentian Violet. 

 T. pavonia var. grandiflora alba: Rather light. 

 T. pavonia var. conchiflora: Rather light, slightly more 

 than in T. pavonia var. grandiflora alba. 



With Safranin. 

 T. pavonia var. grandiflora alba: Rather light. 

 T. pavonia var. conchiflora: Rather light, sUghtly more 

 than in T. pavonia var. grandiflora alba. 



Tempekatuke of Gelatinization. 

 T. pavonia var. grandiflora alba: 60 to 62° C, mean 61''. 

 T. pavonia var. conchiflora: 59 to 61° C, mean 60°. 



Effects op Various Reagents. 

 Reaction with Chloral Hydrate-Iodine. 

 T. pavonia var. grandiflora alba: Begins in all in a 

 minute; complete in four-fifths in 7 minutes, and 

 in all in 12 minutes. 

 T. pavonia var. conchiflora: Begins in all in a minute; 

 complete in all in 7 minutes. 



Reaction with Chromic Acid. 

 T. pavonia var. grandiflora alba: Begins in a few seconds; 



complete in all in 50 seconds. 

 T. pavonia var. conchiflora: Begins in a few seconds; 



complete in all in 45 seconds. 



Reaction with Pyrogallic Add. 



T. pavonia var. grandiflora alba: Begins in a few seconds; 

 complete in all in 55 seconds. 



T. pavona var. conchiflora: Begins in a few seconds; com- 

 plete in all in 50 seconds. 



Reaction with Ferric Chloride. 

 T. pavonia var. grandiflora alba: Begins in a few in 45 



seconds; complete in nearly all in 15 minutes. 

 T. pavonia var. conchiflora: Begins in a few in 45 seconds; 



complete in all in 15 minutes. 



Reaction with Purdy's Solution. 

 T. pavonia var. grandiflora alba: Begins in some in 40 



seconds; complete in all in 25 minutes. 

 T. pavonia var. conchiflora: Begins in some in 45 seconds; 



complete in all in 20 minutes. 



