608 



STARCHES OP IRIDACEiB. 



Iodine Reactions. — ^With 0.25 per cent Lugol's solution the grains all begin to color a fairly 

 deep blue-violet; with 0.125 per cent solution they color lightly, and the color is the same as 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 color a red-violet with an excess of iodine. 



Staining Reactions. — With gentian violet the grains all begin to stain at once and in 30 minutes 

 are lightly stained, but more than the grains of /. florentina. 



With safranin the grains all begin to stain at once and in 30 minutes are fairly stained, but 

 more than the grains of /. florentina. 



Temperature Reaction. — The temperature of gelatinization is 66.5° to 67.5° C, mean 67°. 



Effects of Varimis Reagents. — With chloral hydrate-dodine the reaction begins in 30 seconds. It 

 is over in two-thirds of the grains in 10 minutes and in nearly all in 15 minutes. It is the same 

 qualitatively as that of the grains of /. florentina. 



The reaction with chromic add begins in 15 seconds and is over in 2 minutes. It is the same 

 qualitatively as that of the grains of /. florentina. 



With pyrogaliic acid the reaction begins in 15 seconds and is over in a minute. It is the same 

 qualitatively as that of the grains of I. florentina. 



The reaction with /emc chloride begins in some grains in 15 seconds. It is over in four-fifths of 

 the grains in 10 minutes and in practically all in 15 minutes. It is the same qualitatively as that of 

 the grains of I. florentina. 



Reaction with Purdy's solution begins in 30 seconds and a few are partially gelatinized in 10 



minutes. 



STARCH OF IRIS TINGITANA. (Plate 65, figs. 389 and 390. Chart 263.) 



Histological Characteristics. — In form the grains are usually simple. There are a few compound 

 grains, aggregates, and separated-grains with pressure facets; clumps were not observed. The sur- 

 face of the grains is occasionally irregular, owing chiefly to rounded protuberances or secondary 

 sets of lamellae. The conspicuous forms among the simple grains are the broadly triangular with 

 rounded angles to clam-shell-shaped, and cone-shaped with 

 rounded apex; also a few ovoid and also finger-shaped 

 grains with squared end and a hollowed depression. The 

 conspicuous forms among the compound grains are 

 broadly lenticular and irregularly oval. The aggregates 

 usually appear as doublets, or as triplets in linear arrange- 

 ment, or with one or more minute grains firmly attached 

 to a large one. The separated-grains have well-marked 

 pressure facets and are generally dome-shaped with either 

 squared or pointed base, or are polygonal. The grains 

 are more uniform in shape and much broader in relation 

 to length than in I. florentina, and more closely resemble 

 /. xiphium var. lusitanica. The broadly triangular to 

 clam-shell-shaped grains are somewhat flattened. 



The hilum is a clear, distinct, refractive spot, centric 

 in the small roimd forms, and eccentric two-fifths to one- 

 fourth, usually one-third, of the longitudinal axis in other 

 forms. There is commonly either a cavity or cleft at the 

 hilum. The clefts are oft^n ragged and branched root- 

 like, and frequently form a diagonal cross approaching the flying-bird type previously referred to. 



The lameUoe in the larger forms are rather distinct, but often are not visible on a part of the 

 grain, and two particularly refractive lamellae are frequently observed about one-third to two-thirds 

 of the distance from the hilum. The lamellae in all the grains but the roxmd forms, at a short dis- 

 tance from the hilum, have the shape of the grain and are not very coarse. In round forms 9 lamel- 

 lae forming a band around the margin can be counted, in the medium-sized grains there are 14 to 19 

 distinct lamellae, and in the large ovoid forms there may be as many as 38. 



The graias vary in size; the smaller are 4 by 4/t, the larger are 46 by 34)u and 50 by 28/1 in length 

 and breadth. The common sizes are 30 by 22ju and 32 by 29/i in length and breadth. 



Chart No. 263. 



MINUTES 

 Curve of Reaction-Intensities of Starch of Iris tingitana. 



