IRIS. 



651 



the total starch in 5 minutes; in about 1 per cent of 

 the entire number of grains and 4 per cent of the total 

 starch in 15 minutes; in about the same percentage of 

 the grains and 5 per cent of the total starch in 30 min- 

 utes; in about the same percentage of the grains and 

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

 the same percentage of both the grains and total starch 

 in 60 minutes. (Chart D 409.) 



The reaction with sodium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 28 per 

 cent of the entire number of grains and 50 per cent of 

 the total starch in 2 minutes; in about 46 per cent of 

 the grains and 74 per cent of the total starch in 5 

 minutes ; in about 65 per cent of the grains and 89 per 

 cent of the total starch in 15 minutes; in about 73 per 

 cent in 30 minutes ; in about 77 per cent of the grains and 

 96 per cent of the total starch in 45 minutes ; little if any 

 advance in 60 minutes. (Chart D 410.) 



The hilum becomes very distinct in all the grains. 

 The lamellae also become very distinct, and evidence of 

 a lamellar structure is visible throughout the greater 

 part of the reaction. Gelatinization begins at the hilum 

 which swells somewhat and 2 fissures, which are usually 

 existent in the untreated grain, become more distinct and 

 are seen to extend from either side of the hilum nearly 

 to the distal margin, and during the reaction these fis- 

 sures give out many branches through the portion at 

 the distal end of the grain. The starch comprehended 

 between these fissures is divided into rather fine granules 

 which are usually irregularly arranged. The distal end 

 is now invaded from the margin by longitudinal fissures, 

 and begins to gelatinize, instantly following this the 

 hilum swells and the portion immediately distal to it 

 is gelatinized. The 2 fissures approach one another and 

 the last parti of this portion of the grain to be gelatinized 

 is midway between the hilum and the margin. The most 

 resistant part of the grain is the material at the proxi- 

 mal end and sides nearby, which as the grain swells 

 becomes finely striated and finally forms a distinctly 

 striated and lamellated band at the margin. This is 

 slowly gelatinized and loses its striated appearance but 

 retains its lamellated character, until the end of the 

 reaction is near. The gelatinized grains are moderately 

 swollen, have rather thick capsules, and are moderately 

 distorted. 



.Comparison of the sodium-hydroxide reactions be- 

 tween /. iberica and /. cengialti shows : 



The hilum and lamelke are not so distinct as in 

 /. cengialti. Gelatinization progresses according to two 

 methods, of which the one seen in- the majority of the 

 grains is very nearly the same as that described for all 

 the grains of /. cengialti. The differences noted are: 

 (1) The granules formed in the starch comprehended 

 between the 2 fissures, which extend from the hilum to 

 the distal margin, are finer and often regularly arranged 

 in rows corresponding to the rows of the lamellae; the 

 lamellar structure of the marginal band at the proximal 

 end and sides is not apparent for such a long time as in 

 I. cengialti; (2) the second method is like the first ex- 

 cept that the portion at the distal end and the part 

 just distal to the hilum begin to gelatinize at nearly the 

 same time and the most resistant part of this starch of 

 the grain is that midway between the hilum and the 



distal end. The gelatinized grains are more swollen, 

 have thin capsules, and are more distorted than in I. 

 cengialti. 



The reaction with sodium sulphide begins in a few 

 grains immediately. Complete gelatinization occurs in 

 about 2 per cent of the entire number of grains and 6 

 per cent of the total starch in 5 minutes; in about 18 

 per cent of the grains and 48 per cent of the total starch 

 in 15 minutes ; in about 39 per cent of the grains and 

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

 45 per cent of the grains and 66 per cent of the total 

 starch in 45 minutes; little if any further advance in 

 60 minutes. (Chart D 411.) 



The reaction with sodium salicylate begins imme- 

 diately. Complete gelatinization occurs in about 44 per 

 cent of the entire number of grains and 55 per cent of the 

 total starch in 5 minutes; in about 90 per cent of the 

 entire number of grains and 95 per cent of the total starch 

 in 10 minutes; in about 99 per cent of the grains and in 

 more than 99 per cent of the total starch in 15 minutes. 

 (Chart D 412.) 



The hilum becomes distinct, attended by the for- 

 mation of a rather large bubble in a small majority of 

 the grains. The lamellae are at first indistinct, but 

 later become more distinct. The grains become more 

 refractive in appearance after the addition of the rea- 

 gent, and the first part to show is a rather narrow band 

 at the margin. Gelatinization is preceded by a distinctly 

 pitted appearance of the surface of the grain at the 

 distal end. It begins at the distal corners. From these 

 points it spreads along the entire distal margin and then 

 toward the hilum and proximal end, the material just 

 preceding gelatinization being broken up into granules 

 which are separated off and gelatinized. In the more 

 resistant grains rather large, cup-shaped depressions are 

 hollowed out which become deeper and deeper until the 

 hilum is reached, and then in the rapid gelatinization 

 which occurs are obliterated. The proximal end is 

 usually gelatinized last, but in a moderate number of 

 grains it begins to gelatinize immediately after the distal 

 end and the most resistant portion of the grain is midway 

 between the hilum and the distal margin. 



The gelatinized grains are much swollen, have rather 

 thick capsules, and are considerably distorted. 



Comparison of the sodium-salicylate reaction between 

 7. iberica and /. cengialti shows : 



The hilum becomes distinct, attended by the forma- 

 tion of a smaller bubble in more grains than in /. cen- 

 gialti. The lamella? also are not so distinct as in that 

 starch. The grains become more refractive in appear- 

 ance after the addition of the reagent and the first part 

 of the grain to show this change is a narrow band of 

 material about the margin which is rather more refrac- 

 tive than in I. iberica. Gelatinization progresses in 

 much the same way as in the less resistant grains of 

 7. cengialti, the differences noted being that in many 

 grains of 7. iberica 2 longitudinal fissures proceed from 

 the gelatinized distal margin nearly to the hilum and 

 the material comprehended between them is gelatinized 

 more rapidly than that at the margins. The formation 

 of granules preceding gelatinization is also not seen in 

 any of the grains. The proximal end gelatinizes imme- 

 diately after the distal in fewer grains than in 7. cengialti. 



