GENUS IRIS. 691 



Iodine Reactions. With 0.25 per cent Lugol's solution the grains color fairly deep reddish- 

 violet which deepens rapidly; with 0.125 per cent solution they are colored a very light violet 

 which also deepens rapidly. The color is lighter and has more of a reddish tint than the grains of 

 /. florentina. After heating in water until the grains are completely gelatinized, the solution be- 

 comes a deep indigo-blue and the grains a lighter blue on the addition of iodine. The grains are 

 both lighter and brighter in tint than those of /. florentina. When the grains are boiled for 2 minutes 

 and then treated with iodine, the solution colors a deep reddish-blue and the gelatinized grains a 

 rather light blue, sometimes with a reddish tint. With an excess of iodine the grain-residues color 

 a deep reddish-blue and the capsules a deep reddish heliotrope. The solution has more, and the 

 grains and capsules less, of a reddish tint than /. florentina. 



Staining Reactions. \Yith gentian violet the grains exhibit a very faint trace of violet at once 

 and in 30 minutes are very lightly colored. The color is considerably lighter than in the grains of 

 /. florentina. 



With safranin the grains exhibit a very faint trace of pink immediately and in 30 minutes are 

 lightly stained. The color is less than in the grains of /. florentina, but the difference is not so great 

 as in the case of gentian violet. 



Temperature Reaction. The temperature of gelatinization is 74 to 75 C, mean 74.5. 



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

 30 seconds. It is complete in about half in 5 minutes, in the majority in 7 minutes, in nine-tenths 

 in 10 minutes, and in all but a few resistant grains in 15 minutes, in which the reaction may not be 

 completed for 20 to 25 minutes. The reaction is qualitatively the same as in I. florentina. 



With chromic acid the grains begin to swell in 20 seconds. A few are dissolved in 40 seconds, 

 the majority in a minute, and all in 2 minutes. Refractive granules are frequently observed during 

 gelatinization of the grains, but the entire grain is finally dissolved. The reaction is qualitatively 

 the same as in I. florentina. 



Reaction with pyrogallic acid begins immediately. A few grains are gelatinized in 20 seconds, 

 the majority in 40 seconds, all but a few resistant grains in a minute, and all in IJ^ minutes. The 

 reaction is qualitatively the same as in /. florentina. 



With ferric chloride a few grains begin to swell in 30 seconds. A small number are gelatinized 

 in 2 minutes, about one-third in 5 minutes, nine-tenths in 10 minutes, and all but a few resistant 

 grains in 15 minutes. A small portion of the starch at the proximal end is occasionally not gelati- 

 nized, while in I. florentina the gelatinization is generally complete. The reaction is qualitatively 

 the same as in I. florentina. 



The reaction with Purdy's solution begins in a few grains in 30 seconds. A small number are 

 gelatinized in 5 minutes, and about one-tenth in 15 minutes, but after this time, up to 30 minutes, 

 there is very little progress. The hilum is swollen in the grains not gelatinized and a longitudinal 

 fissure usually extends obliquely from each side of it, between which the lamella; have become 

 more distinct. During gelatinization the grains do not frequently spread out laterally, bell-shape, 

 at the distal end, as in /. florentina, but gelatinization gradually advances towards the proximal 

 end between the two longitudinal fissures already noted and is accompanied by less distortion of 

 the grain. The reaction is qualitatively the same as in /. florentina. 



STARCH OF IRIS PUMILA VAR. CYANEA. (Plate 63, figs. 377 and 378. Chart 257.) 



Histological Characteristics. In form the grains are usually simple and isolated, and a few have 

 pressure facets; a number are found in the form of small aggregates, compound grains of few com- 

 ponents, and in clumps, the latter consisting generally of minute grains. The surface of the grains 

 is often irregular, owing to the same causes noted under I. florentina. The conspicuous forms of 

 the simple grains are the finger-shaped with hollow distal end, elongated ovoid with similar distal 

 end, irregular elhpsoidal, and pyriform; also dome-shaped, spatula-shaped, round grains of medium 

 size, cone-shaped with rounded apex, and irregular grains of definite shape. As a result of secondary 

 deposits upon the primary grains, various shapes are found among the grains, such as noted under 

 /. florentina. The compound grains and aggregates are also of similar character to those described 

 under /. florentina. The grains are mostly elongated and are more irregular in outline than those 

 of /. florentina. 



The hilum is observed as a distinct round or elliptical spot, usually one-sixth to one-tenth 

 eccentric of the longitudinal axis. It is not generally so refractive nor so often fissured as in /. floren- 



