692 



STARCHES OF miDACB^. 



Una. Sometimes either a short transverse or diagonal fissure is found at the hilum, and occasionally 

 one delicat« longitudinal fissure runs obliquely from each side of the hilum. 



The lamelloe are usually fine and indistinct. When demonstrable they form complete rings 

 around the hilum, but beyond this region they assume the shape of the margin of the grain and are 

 probably incomplete. One or more secondary sets of lamellse are frequently found at varying 

 angles to the primary set. On the large grains 28 to 32 lamellae have been counted. 



The grains vary in size; the smaller are 3 by 2/t; the larger are 40 by 14^1 in length and breadth. 

 The common size is 30 by 13/i in length and breadth. 



Polariscopic Properties. — The figure is usually eccentric. It is generally clear-cut, and the 

 lines are of similar character to those noted for /. florentina, but more often bent or bisected. 



The degree of polarization is high. There Is a variation in the grains, in some of which polari- 

 zation is very high. The same variation is noted as in /. florentina in the one aspect of a given 

 grain. The degree of polarization is distinctly higher 

 than in /. florentina. 



With selenite the quadrants are well defined, unequal 

 in size, and more often irregular in shape than in the 

 grains of /. florentina. The colors are generally pure, 

 about the same as in those of /. florentina. 



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

 tion the grains color a fairly deep violet, which deepens 

 rather rapidly; with 0.125 per cent solution they color a 

 very light violet which deepens rather rapidly. The reac- 

 tion is of about the same intensity as in /. florentina. 

 After heating in water until the grains are gelatinized, 

 the solution colors a deep greenish-blue and the grains a 

 deep blue with a reddish tint on the addition of iodine. 

 If the grains are boiled for 2 minutes and then treated 

 with iodine, the solution colors a deep indigo-blue and 

 the grain-residues a deep purple. With an excess of 

 iodine the capsules color a deep old-rose to wine-red. 

 The gelatinized grains and the capsules have more of a 

 reddish tint than in /. florentina. 



Staining Reactions. — With gentian violet the grains show a faint trace of violet immediately 

 and in 30 minutes are lightly stained. The tint is about the same as in /. florentina. 



With safranin the grains stain faintly at once and in 30 minutes are lightly colored. The tint 

 is about the same as in /. fl^entina. 



Temperature Reaction. — The temperature of gelatinization is 72.5° to 74° C, mean 73.2°. 



Effects of Various Reagents. — With chloral hydrate-iodine a few grains begin to react in 30 seconds. 

 About half are gelatinized and there is reaction in practically all in 5 minutes; about nine-tenths are 

 gelatinized in 10 minutes, and all in 15 minutes, excepting the rare resistant grains, which may not be 

 completely gelatinized for 25 to 40 minutes. The reaction is qualitatively the same as in I. florentina. 



The reaction with chromic add begins inunediately. A few are dissolved in 20 seconds, the 

 majority in 40 seconds, and nearly all in l}/^ minutes, excepting rare resistant grains in which re- 

 action takes 3 minutes for completion. The reaction is qualitatively the same as in /. flarentina. 



Reaction with pyrogallic acid begins at once. Many are gelatinized in 20 seconds; the majority 

 in 40 seconds and all but a few resistant grains in a minute, and it is complete in the latter in 2 

 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 half in 5 minutes, nine-tenths in 10 minutes, and nearly all in 15 minutes, 

 with the exception of a small amount of starch at the proximal end, which is not gelatinized even 

 in 30 minutes. 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 2 minutes and very gradual progress occurs in 5 minutes. About one-tenth are gelat- 

 inized and there is partial gelatinization of about one-half in 10 minutes. About one-fifth are 

 gelatinized and two-thirds are partially gelatinized in 15 minutes. The reaction is qualitatively 

 the same as in /. florentina. 



Curve of Reaction-Intensities of Starch of Iris pumila 

 var. cyanea. 



