694 



STARCHES OF IRIDACE^. 



Reaction with Furdy's solution begins in 30 seconds. Two-thirds arc nearly completely gelati- 

 nized in 2 minutes and four-fifths are gelatinized in 10 minutes. The reaction is the same qualita- 

 tively as that of the grains of /. florentina. 



STARCH OF IRIS IBERICA. (Plate 64, figs. 381 and 382. Chart 259.) 



Histological Characteristics. In foryn the grains are mostly simple. There are some compound 

 grains, aggregates usually in the form of doublets, separated grains with pressure facets, and clumps 

 consisting of very small grains. The surface is often irregular, owing to the causes noted in the 

 grains of /. florentina. The conspicuous forms are similar to those observed in /. florentina, but the 

 simple grains are neither so elongated nor so slender, and are more regular, because secondary sets of 

 lamellae are not so frequent. Among the compound grains a broadly lenticular form with rounded 

 ends is frequently present, besides the forms noted for /. florentina. The resemblances as a whole 

 to I. hismarckiana are closer than to I. florentina. 



The hiluni is a distinct refractive spot, centric in the small, round grains, and eccentric in the 

 larger grains from one-fifth to one-seventh, usually one-fifth, of the longitudinal axis. Two hila 

 without a fine of separation are sometimes found in a simple grain. Two short longitudinal fissures 

 frequently run from the hilum. A cavity may appear at 

 the hilum, but usually tliere is an absence of clefts. 



The lamellce are not distinct. It is impossible to 

 determine with any definiteness either their character 

 or number. 



There is a variation in size; the smaller are 4 by 4//; 

 the larger measure 28 by 16yu in length and breadth. The 

 common size is 18 by lO^u in length and breadth. 



Polariscopic Properties. The flgure is usually eccen- 

 tric and distinct. Its lines are rather fine and sometimes 

 straight, but often bent or bisected. It is fairly clear-cut, 

 and regular in more of the grain than in I. florentina. 



The degree of polarization is fairly higli. There is 

 some variation in the different grains and occasionally in 

 the same aspect of a given grain. It is higher than in 

 I. florentina. 



With selenite the quadrants are usually unequal m 

 size and vary somewhat in shape. The colors are pure, 

 purer than in I. florentina. 



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

 tion the grains all begin to color a fairly deep violet; with 0.125 per cent solution they color lightly 

 and the color does not deepen rapidly. The color is less than that of the grains of /. florentina. 

 After heating in water until the grains are completely gelatinized, the solution colors fairly deeply 

 and the gelatinized grains very deeply on the addition of iodine. After boiling for 2 minutes the 

 solution colors very deeply, but most of the grain-residues not at all. The capsules all color a deep 

 red-violet with an excess of iodine. 



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

 and in 30 minutes are lightly stained. The stain is slightly more than that of the grains of /. florentina. 



Temperature Reaction. The temperature of gelatinization is 72.2 to 74 C, mean 73.1. 



Effects of Various Reagents. With chloral hydrate-iodine reaction begins in a few grains in 30 

 seconds and in most in a minute. One-third are gelatinized in 3 minutes and all in 15 minutes. It 

 is the same qualitatively as that of the gi-ains of /. florentina. 



The reaction \vith chromic acid begins in 15 seconds and is over in 2 minutes. It is the same 

 qualitatively as that of the grains of /. florentina. 



Reaction with pyrogalUc acid begins in 20 seconds and is over in 2V2 minutes. It is the same 

 qualitatively as that of the grains of /. florentina. 



Reaction with ferric chloride begins in some grains in a minute and is over in 12 minutes. It is 

 the same qualitatively as that of the grains of /. florentina. 



With Purdy's solution a few of the grains begin to react in 1}^ to 2 minutes, and a few are 

 partially gelatinized in 15 minutes. It is the same qualitatively as that of the grains of /. florentina. 



MINUTES 

 Curve of Reaction-Intensities of Starch of Iris iberica. 



