IRIS. 



669 





purpurea. If the preparation is boiled for 2 minutes 

 and then treated with an excess of a 2 per cent Lugol's 

 solution, most of the grain-residues are not colored except 

 the capsules, and many less grain-residues than in I. per- 

 sica var. purpurea are colored a light indigo ; the capsules 

 are all colored a reddish violet, less than in /. persica 

 var. purpurea; and the solution a very deep indigo as in 

 I. persica var. purpurea. 



ANILINE REACTIONS. 



With gentian violet the grains usually stain very 

 lightly at once, less than in /. persica var. purpurea, and 

 in 30 minutes they are moderately colored (value 42), 3 

 units less than in /. persica var. purpurea. There is 

 a greater proportion of the grains light to moderately 

 stained than in /. persica var. purpurea. 



With safranin the grains as in I. persica var. purpurea 

 stain very lightly at once, and in 30 minutes they are 

 moderately colored (value 47), 3 units less than in I. 

 persica var. purpurea. 



TEMPERATURE REACTIONS. 



The temperature of gelatinization of the majority 

 of the grains is 63.5 to 65 C., and of all 66 to 

 67 C., mean 66.5 C. This is 2.5 C. less than that of 

 I. persica var. purpurea. 



EFFECTS OF VARIOUS REAGENTS. 



The reaction with chloral hydrate begins in 1 minute. 

 Complete gelatinization occurs in about 8 per cent of the 

 entire number of grains and 10 per cent of the total starch 

 in 5 minutes ; in about 9 per cent of the grains and 12 per 

 cent of the total starch in 15 minutes ; in about 20 per 

 cent of the grains and 24 per cent of the total starch in 30 

 minutes ; in about the same percentage of the grains and 

 25 per cent of the total starch in 45 minutes; in about 

 27 per cent of the grains and 30 per cent of the total 

 starch in 60 minutes. (Chart D 442.) 



The hilum is as distinct as in I. persica var. purpurea, 

 and a bubble is often formed there, but not so often 

 as in 7. persica var. purpurea. The lamellae, at first, 

 are not distinct, but later become more distinct than in 

 J. persica var. purpurea. The grains, as in I. persica var. 

 purpurea, become more refractive in appearance as the 

 reaction progresses, and the first portion to show this is 

 the marginal starch which forms a narrow, refractive 

 band around the entire grain. Gelatinization begins at 

 the margin as in /. persica var. purpurea, but usually 

 only at two points, and there are no cracks or fissures as 

 noted in that starch. In some of the elongated forms 

 2 longitudinal fissures extend toward the hila from the 

 distal margin; in the majority, however, the marginal 

 portion between the two points already mentioned is 

 gelatinized, and then gelatinization proceeds smoothly 

 toward the proximal end, and the surface being less 

 resistant than the interior is gelatinized first, produc- 

 ing a cone-shape on the distal end of the ungelatinized 

 starch. When the hilum is reached, the bubble if 

 present swells, shrinks, and then disappears, and the 

 rest of the reaction is the same as already described 

 under I. persica var. purpurea. The gelatinized grains 

 are large, thicker walled, and not so much distorted as in 

 I. persica var. purpurea, and they retain more resem- 

 blance to the form of the untreated grain. 



The reaction with chromic acid begins in 30 seconds. 

 Complete gelatinization occurs in about 5 per cent of the 

 entire number of grains and 25 per cent of the total 

 starch in 5 minutes; in about 37 per cent of the grains 

 and 85 per cent of the total starch in 15 minutes; in 

 about 40 per cent of the grains and 92 per cent of the 

 total starch in 30 minutes; in about 57 per cent of the 

 grains and 97 per cent of the total starch in 45 minutes ; 

 in about 80 per cent of the grains and 98 per cent of the 

 total starch in 60 minutes. (Chart D 443.) 



The .reaction with pyrogallic acid begins in 30 sec- 

 onds. Complete gelatinization occurs in about 25 per 

 cent of the entire number of grains and 71 per cent of 

 the total starch in 5 minutes ; in about 88 per cent of the 

 grains and 98 per cent of the total starch in 15 minutes; 

 in about 94 per cent of the grains and 99 per cent of the 

 total starch in 30 minutes. (Chart D 444.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in about 53 per cent of 

 the entire number of grains and 90 per cent of the total 

 starch in 5 minutes; in about 65 per cent of the grains 

 and 98 per cent of the total starch in 15 minutes ; in about 

 85 per cent of the grains and 99 per cent of the total 

 starch in 30 minutes ; little if any further advance in 45 

 and 60 minutes, respectively. (Chart D445.) The 

 margin of a small percentage of grains is quite resistant 

 as in /. persica var. purpurea. 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 91 per cent of 

 the entire number of grains and 97 per cent of the total 

 starch in 2 minutes; in more than 99 per cent of the 

 grains and total starch in 5 minutes. (Chart D 446.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 87 per 

 cent of the entire number of grains and 98 per cent of the 

 total starch in 5 minutes ; in more than 99 per cent of the 

 grains and total starch in 15 minutes. (Chart D 447.) 



The hilum is as distinct as in I. persica var. purpurea, 

 and there is not so frequently a bubble as in the starch. 

 The lamellae are distinct, but not quite so distinct as in 

 7. persica var. purpurea. Gelatinization, as in I. persica 

 var. purpurea, begins at the hilum and the two methods 

 of procedure noted in that starch are also seen here. 

 In the first, the strias are very much finer and less prom- 

 inent, but the lamellae remain visible much longer and 

 2 or 3 may be seen in the nearly transparent marginal 

 band long after gelatinization is otherwise apparently 

 complete. In the second type the refractive fissures are 

 not so refractive, so prominent, or so branched as in 

 7. persica var. purpurea, and the distal material is often 

 invaded by several fissures from the margin which appa- 

 rently make it less resistant as gelatinization starts at 

 the hilum and then quickly at the distal margin, and the 

 two reactions meet approximately midway between the 

 hilum and the distal margin. 



The gelatinized grains are much swollen, have thin- 

 ner capsules, and are somewhat more distorted than in 

 7. persica var. purpurea, and do not retain as much 

 resemblance to the form of the untreated grain as 7. 

 persica var. purpurea. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 62 

 per cent of the entire number of grains and 85 per cent 

 of the total starch in 5 minutes ; in about 80 per cent of 



