GENUS WATSONIA. 



725 



Differentiation of Certain Starches of the Genus Watsonia. 



Histological Characteristics. 

 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 W. 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 sUghtly eccentric. 



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

 as in W. humilis. Position usually slightly eccen- 

 tric. 



IF. meriana: Form essentially the same a-s in Tl'. humilis. 

 Position usually eccentric. 



Lamellce 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. 



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

 W. humilis. 6 to S 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 1.5 to 2Sm; doublets 16m. 



IF. iridifolia var. o'brieni: Single 2 to 30m; doublets 20m. 



IF. meriana: Single 3 to 34m; doublets 22m. 



PoLARiscopic Properties. 



Figure. 



W. humilis: Usually somewhat eccentric, distinct and 



generally clear-cut, fairly regular; large dark area 



common. 

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



IF. humilis, but usually absence of large dark 



area. 

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



dark area less marked. 



Degree of Polarization. 



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

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



than in IF. humilis. 

 IF. meriana: High, varies somewhat, higher than in 



IF. humilis. 



Polarization with Selenite Quadrants and Colors. 



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



irregular, somewhat unequal in size. Colors 



generally pure. 

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



fairly regular and fairly equal in size. Colors 



pure. 

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



fairly equal in size. Colors pure. 



Iodine Reactions. 

 Intensity and Color. 

 IF. humilis: Light; violet. 

 IF. iridifolia var. o'brieni: Light, sUghtly deeper than 



in IF. humilis; violet. 

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



Staining Keactions. 

 With Gentian Violet. 

 IF. humilis: Fairly deep. 

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



in IF. humilis. 

 IF. meriana: Fair, not so deep as in IF. humilis. 



With Safranin. 

 IF. humilis: Fairly deep. 

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



in IF. humilis. 

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



Temperature of Gelatinization. 

 W. humilis: 75 to 76 C, mean 75.5. 

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

 H'. meriana: 75.5 to 77 C, mean 76.25. 



Effects of Various Reagents. 

 Reaction with Chloral Hydrate-Iodine. 



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

 complete in small and medium-sized grains in 20 

 minutes. Larger grains unaffected. 



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

 um-sized grains in 5 minutes; all the small and 

 medium-sized grains complete in 15 minutes. Very 

 few of larger grains at all affected. 



IF. meriana: Begins in aU 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 tvith Chromic Acid. 

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

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



in 3 minutes. 

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



5 minutes. 



Reaction with Pyrogallic Acid. 



IF. humilis: Begins in 13/2 minutes; complete in 13 

 minutes. 



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

 plete in 10 minutes. 



IF. meriana: Begins in 13^ to 2 minutes; complete in 15 

 minutes. 



Reaction with Ferric Chloride. 

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



40 minutes. 

 IF. iridifolia var. o'brieni: Begins in some in 2}^ minutes; 



complete in 45 minutes. 

 IF. meriana: Begins in some in 2 minutes; complete in 



45 minutes. 



Reaction with Purdy's Solution. 



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



IF. iridifolia var. o'brieni: Slight reaction in some in 5 

 minutes; shght swelling of affected grains; no fur- 

 ther change. 



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

 no further change. 



NOTES ON THE STARCHES OF WATSONIA. 

 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 



