GENUS WATSONIA. 



723 



p I Gv r p 

 s 



Chart No. 277 



GV 



CI CA PA FC P S CI PA CA 

 " ~~ POPS 



secondarj' layers of starch so that the outlines of the grain have become entirely different from the 

 original. There are aboiit 6 to 8 lamellae on the larger grains, and those near the hilum are the more 

 distinct. 



The isolated grains vary in size from 2 to 18/i and the aggregates up to 30^1. The common size 

 of the isolated grains is lOju and of the doublets 20ix. 



Polariscopic Properties. The figure is generally clear-cut, distinct, and fairly regular. Its 

 lines may become somewhat broader, but less defined at the margin of the grain, and may be 

 slightly bent or otherwise distorted. Where there are two or more hila, two or more figures may 

 be observed. There is usually an absence of the large, dark central area referred to in W. humilis. 



The degree of polarization is high; as a whole, somewhat higher than that in the grains of W. 

 humilis. It varies somewhat in different grains, but not greatly in different aspects of the same grain. 



With selenite the quadrants are, as a rule, clear-cut, 

 fairly regular in shape, and fairly equal in size. The 

 colors are pure. 



Iodine Reactiotis. With 0.25 per cent Lugol's .solu- 

 tion the grains are colored lightly, but the color is deeper 

 than that of W. hiwiilis; with 0.125 per cent solution the 

 grains color lightly and do not deepen readily, but the 

 color is deeper than that of the grains of W. humilis. 

 After heating until the grains are completely gelatinized, 

 the solution is fairly colored and the grains very deeply 

 with iodine. After boiling for 2 minutes both the solu- 

 tion and the grain-residues are ver_v deeply colored. If 

 an excess of iodine is added, some of the more lightly col- 

 ored grains show a violet capsule. 



Staining Reactions. With gentian violet and with 

 safranin the grains begin to stain fairly deeply at once, 

 but after 30 minutes the tint is not much deeper. It is 

 the same as that of W. humilis. 



Temperature Reaction. The temperature of gelatin- 

 ization is 74 to 75 C, mean 74.5. 



Effects of Various Reagents. With chloral hydrate-iodine there is reaction in some of the smaller 

 grains in a minute; many medium-sized grains are affected in 5 minutes; almost all the small and the 

 medium-sized grains are darkened, but only very few of the larger grains are affected in 15 minutes. 

 There is practically no further change. The reaction is practically identical qualitatively with that 

 of the grains of W. humilis. 



The reaction with chromic acid begins in many grains in a minute and is over in 3 minutes. 

 It is practically identical qualitatively with that of the grains of W. humilis. 



With pyrogallic acid there is a slight general reaction in 2 minutes and all the grains are com- 

 pletely gelatinized in 10 minutes. The reaction is qualitatively the same as that in the grains of 

 W. humilis. 



There is a reaction with ferric chloride in some grains in 2}^ minutes. All are affected and most 

 of them partially gelatinized in 30 minutes, and all are gelatinized in 45 minutes. The reaction is 

 practically identical qualitatively with that of W. humilis. 



There is with Purdy's solution a slight reaction of a few grains in 5 minutes. A few more may 

 afterwards be affected and there may be a slight increase in the signs of swelling, but otherwise 

 there is no fm-ther change. 



STARCH OF WATSONIA MERIANA. (Plate 70, figs. 419 and 420. Chart 278.) 



Histological Characteristics. In form the grains are simple, and are isolated with the exception 

 of most or all of the larger grains, which consist of two or more components. The very small grains 

 are numerous, but not nearly so abundant relatively as in W. humilis. The .surface is quite regular, 

 and there are very few isolated grains having pressure facets. The conspicuous forms are the oval 

 to ovoid, to spherical or nearly spherical. There are a few rounded, triangular, pyriform, and hemi- 

 spherical grains. The very small grains are mostly spherical or polygonal. The larger grains are 

 not flattened and appear spherical on end. 



Curve of Reaction-Intensities of Starch of Watsonia 

 iridifolia var. o'brieni. 



