GENUS IRIS. 699 



Polariscopic Properties. The figure is generally eccentric and quite distinct. Its lines are 

 rather thick and generally straight with broadening towards the margin, and occasionally are bi- 

 sected. It is fairly clear-cut, and more distinct and regular than in /. florenlina. 



The degree of -polarization is high to very high, sometimes varying in the same aspect of a given 

 grain. It is decidedly higher than in /. florentina. 



With selenite the quadrants are well defined, often slightly irregular in shape, and unequal in 

 size. The colors are generally pure, but the yellow is sometimes not quite pure. They are purer 

 than in /. florentina. 



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

 blue; with 0.125 per cent solution they color lightly and the color does not deepen rapidly. It 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 

 do not color at all. The capsules all color a red-violet with an excess of iodine. 



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

 and in 30 minutes are lightly stained, slightly more than the grains of /. florentina. 



Temperature Reaction. The temperature of gelatinization is 65 to 66 C, mean 65.5. 



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

 seconds. One-half of the grains are gelatinized in 10 minutes, three-fourths in 15 minutes, and 

 practicallj' all in 25 minutes. It is the same qualitatively as that of the grains of I. florentina. 



The reaction with chromic acid begins in some grains in a few seconds and in all the rest 

 in 20 seconds, and it is over in 2J4 minutes. It is the same qualitatively as that of the grains of 

 /. florentina, except that the capsule is quite as likely to be dissolved first at the proximal as at 

 the distal end. 



Reaction with pyrogallic acid begins in all the grains in 15 seconds and is over in a minute. It 

 is the same qualitatively as that of the grains of /. florenlina, except that a bubble is practically 

 always formed at the hilum, and that when this bubble decreases in size it leads to an invagination 

 of the capsule at the proximal end, to be followed by the reverse movement. 



The reaction with ferric chloride begins in a few grains in 30 to 45 seconds. It is over in four- 

 fifths of the grains in 10 minutes and in all in 20 minutes. It is the same quahtatively as that of the 

 grains of /. florentina. 



The reaction with Purdy's solution begins in all the grains in 30 seconds and a few are nearly 

 completely gelatinized in 5 minutes. One-third are nearly completely gelatinized in 15 minutes, and 

 three-fifths of the remaining two-thirds are partially gelatinized. 



STARCH OF IRIS RETICULATA. (Plate 66, figs. 391 and 392. Chart 264.) 



Histological Characteristics. In form the grains are usually simple. There are some compound 

 grains, aggregates, and separated-grains with pressm-e facets; clumps composed chiefly of minute 

 globular grains are also observed. The surface of the grains is often irregular. The margin of the 

 grain frequently is undulating; there are irregularities due to secondary deposits, and rounded 

 protuberances as in I. florentina. The conspicuous forms are the cone-shaped with rounded apex, 

 pjrriform with a squared end, minute and fair-sized globular, and oval with or without a squared end; 

 also a few elongated, slender grains similar to tho.se observed in /. florentina. Among the compound 

 grains there is an irregular oval form, as well as forms similar to those of /. florentina. The aggre- 

 gates frequently consist of one large with one or more minute, globular grains; and occasionally 

 of grains of equal or nearly equal size. The grains are broader in proportion to length and less 

 irregular than those of /. florentina. 



The hilmn may be observed as a clear, distinct, round, refractive spot, centric in the round 

 forms, and in most of the grains eccentric from slightly to two-fifths to one-third, usually two-fifths, 

 of the longitudinal axis. Either a cavity or a cleft commonly is to be seen at the hilum. The clefts 

 are generally ragged and irregular; sometimes two are so arranged as to form a cross. 



The lamella are rather fine but distinct. They form complete, regular rings around the hilum, 

 but farther out have the shape of the outline of the grain, and are probably not complete near the 

 distal margin. There are 22 laraellfe on the grains of fair size. 



The grains vary in size; the smaller are 11 by 4/^; the larger are 46 by 36ai and 40 by M/j. in 

 length and breadth. The conamon sizes are 30 by 22/:i and 32 by 26fi in length and breadth. 



