GENUS WATSONIA. 



725 



Differentiation of Certain Starches of the Genus Walsonia. 



Histological Chabacteristics. 



Conspicuous Forms. 



W. humilis: Simple, except small grains almost wholly 

 in the form of aggregates of 2 or more components, 

 probably some compound grains, very few isolated 

 grains with pressure facets. Aggregates ovoid and 

 spherical, with transitional forms, small grains 

 exceptionally abundant. 



W. iridifolia var. o'brieni: Essentially the same as in 

 W. humilis, but the conspicuous aggregates are 

 ovoid to elliptical and rounded triangular. Small 

 grains fairly numerous. 



W. meriana: Essentially the same as in TT. humilis, 

 but the conspicuous aggregates are the oval to 

 ovoid, to spherical or nearly spherical. Small 

 grains not nearly so numerous. 



Hilum — Form, Number, and Position. 



W. humilis: Form large, usually very distinct, usually 

 round, may be a cavity, may be fissured. Posi- 

 tion usually slightly eccentric. 



W. iridifolia var. o'brieni: Form essentially the same 

 as in W. humilis. Position usually sUghtly eccen- 

 tric. 



W. meriana: Form essentially the same as in TF. humilis. 

 Position usually eccentric. 



Lamellm — General Characteristics and Number. 



W. humilis: Fairly distinct, rather coarse, usually regu- 

 lar, continuous concentric rings, more distinct 

 near the hilum. 8 to 9 on larger grains. 



ir. iridifolia var. o'brieni: Essentially the same as in 

 W. humilis. 6 to 8 on larger grains. 



W. meriana: Essentially the same as in W. humilis, but 

 less distinct. 5 to 6 on larger grains. 



Size. 



W. humilis: Single 1.6 to 28^; doublets 16yu. 



W. iridifolia var. o'brieni: Single 2 to 30;u; doublets 20/i. 



W. meriana: Single 3 to 34m; doublets 22/1. 



POLARISCOPIC PrOPBUTIES. 



Figure. 



W. humilis: Usually somewhat eccentric, distuict and 



generally clear-cut, faiily regular; large dark area 



common. 

 W. iridifolia var. o'brieni: Essentially the same as in 



W. humilis, but usually absence of large dark 



area. 

 W. meriana: Essentially the same as in IF. humilis, but 



dark area less marked. 



Degree of Polarizaiion. 



W. humilis: Fairly high, varies much in different grains. 

 W. iridifolia var. o'brieni: High, varies somewhat, higher 



than in W. humilis. 

 W. mertarm: High, varies somewhat, higher than in 



W. humilis. 



Polarizaiion loilh Seknile — Quadrants and Colors. 

 W. humilis: Quadrants usually not clear-cut, generally 



irregular, somewhat unequal in size. Colors 



generally pure. 

 W. iridifolia var. o'brieni: Quadrants usually clear-cut, 



fairly regular and fairly equal in size. Colors 



pure. 

 W. meriana: Quadrants fairly clear-cut, fairly regular, 



fairly equal in size. Colors pure. 



Iodine Rbactionb. 



Intensity and Color. 

 W. humilis: Light; violet. 

 W. iridifolia var. o'brieni: Light, slightly deeper than 



in W. humilis; violet. 

 W. meriana: Light, lighter than in W. humilis; violet. 



Staining Reactions. 

 With Gentian Violet. 

 W. humilis: Fairly deep. 

 W. iridifolia var. o'brieni: Fairly deep, little deeper than 



in W. humilis. 

 W. meriana: Fair, not so deep as in TT. humilis. 



With Safranin. 

 W. humilis: Fairly deep. 

 W. iridifolia var. o'brieni: Fairly deep, little deeper than 



in W. humilis. 

 W. meriana: Light, not so deep as in W. humilis. 



Temperature of Gblatinization. 



W. humUis: 75 to 76° C, mean 75.5°. 



W. iridifolia var. o'brieni: 74 to 75° C, mean 74.5°. 



W. meriana: 75.5 to 77° C, mean 76.25°. 



Effects of Various Reagents. 

 Reaction with Chloral Hydrate-Iodine. 



W. humilis: Begins in the smaller grains in 5 minutes; 

 complete in small and medium-sized grains in 20 

 minutes. Larger grains unaffected. 



W. iridifolia var. o'brieni: Begins in all small and medi- 

 um-sized grains in 6 minutes; all the small and 

 medium-sized grains complete in 15 minutes. Very 

 few of larger grains at all affected. 



W. meriana: Begins in all small and in a few medium- 

 sized grains in 5 minutes; complete in all the 

 small and in a few medium-sized grains in 20 

 minutes; very few large grains at all affected. 



Reaction with Chromic Add. 

 W. humilis: Begins in a minute; complete in 4 J^ minutes. 

 W. iridifolia var. o'brieni: Begins in a minute; complete 



in 3 minutes. 

 W. meriana: Begins in 30 to 60 seconds; complete in 



5 minutes. 



Reaction with Pyrogallic Acid. 



W. humilis: Begins in 1}^ minutes; complete in 13 

 minutes. 



W. iridifolia var. o'brieni: Begins in 2 minutes; com- 

 plete in 10 minutes. 



W. meriana: Begins in IJ^ to 2 minutes; complete in 15 

 minutes. 



Reaction leith Ferric Chloride. 

 W. humilis: Begins in some in IK minutes; complete in 



40 minutes. 

 TF. iridifolia var. o'brieni: Begins in some in 2J^ minutes; 



complete in 45 minutes. 

 W. meriarux: Begins in some in 2 minutes; complete in 



45 minutes. 



Reaction with Purdy's SolvXion. 



W. humilis: Begins in some in 5 minutes ; no further change. 



TF. iridifolia var. o'brieni: SUght reaction in some in 6 

 minutes; sUght swelling of affected grains; no fur- 

 ther change. 



W. meriana: Slight reaction in one-fourth in 15 minutes; 

 no further change. 



NOTES ON THE STARCHES OF WATSONLV. 



Such differences as have been recorded in the gross histological characters of these starches 

 are of a minor nature and probably entirely incidental, and therefore likely of no real diagnostic 



