IRIS. 



659 



the total starch in 5 minutes; in about 28 per cent of 

 the grains and 75 per cent of the total starch in 15 

 minutes ; in about 47 per cent of the grains and 83 per 

 cent of the total starch in 30 minutes; in about 50 per 

 cent of the grains and 88 per cent of the total starch in 

 45 minutes; in about 55 per cent of the grains and 90 

 per cent of the total starch in 60 minutes. (Chart 

 D478.) 



The hilum becomes very distinct in all the grains. 

 The lamellae also are distinct. Two fissures which pre- 

 exist in the untreated grain become more conspicuous 

 and are seen to extend from the hilum to the distal mar- 

 gin. The starch comprehended between these two fis- 

 sures is divided by irregular fissures into a number of 

 irregular, refractive granules. Gelatinization follows 

 two methods. In the great majority of the grains the 

 material at the distal end 'begins to gelatinize first and 

 gelatinization proceeds from this point to the hilum, the 

 fissures and the granules becoming more distinct as the 

 grain swells. The starch at the proximal margin and 

 sides forms a homogeneous-looking band as the grain 

 swells and this is the most resistant part of the grain. 

 It gradually becomes thinner and more nearly trans- 

 parent until it is completely gelatinized. In the second 

 method, the hilum swells and the granular starch com- 

 prehended between the 2 original fissures is gelatinized 

 at the hilum and then gradually toward the distal end. 

 The material at the proximal end and sides forms a 

 homogeneous-looking, refractive band at the margin 

 which gradually grows thinner and more nearly trans- 

 parent until it is gelatinized and only the capsule 

 remains. 



The gelatinized grains are moderately swollen, have 

 rather thick capsules, and are not greatly distorted. 



Comparison of the potassium-iodide reactions between 

 7. cengialti and I. pallida queen of may shows : 



The hilum is as distinct and the lamella? are some- 

 what more distinct than in I. pallida queen of may. 

 Gelatinization proceeds according to two methods. The 

 first, which is seen in a large majority of the grains, 

 differs from that described for a very large majority of 

 the grains of I. pallida queen of may in that gelatiniza- 

 tion begins at the distal end and then at the hilum and 

 the two processes approach one another, the most resist- 

 ant part of this portion of the grain being about half 

 the distance between the hilum and the distal end. The 

 second method, which is seen in more grains than in I. 

 pallida queen of may, is the same as the second method 

 described in that grain. In all the grains the granules 

 formed previous to gelatinization are finer and arranged 

 in rows corresponding to the rows of the lamella?, instead 

 of irregularly as in I. pallida queen of may. The gela- 

 tinized grains are moderately swollen and have somewhat 

 thicker capsules, but are no more distorted, than in that 

 starch. 



The reaction with potassium sulphocyanate begins 

 immediately. Complete gelatinization occurs in about 

 40 per cent of the entire number of grains and 75 per 

 cent of the total starch in 2 minutes; in about 51 per 

 cent of the grains and 89 per cent of the total starch 

 in 5 minutes ; in about 66 per cent of the grains and 95 

 per cent of the total starch in 15 minutes; in about 68 

 per cent of the grains and 96 per cent of the total starch 

 in 30 minutes. (Chart D429.) 



(Note. — The grama aro nuickly gelatinized with the excep- 

 tion of a narrow band al the proximal end and sides nearby 

 and a few scattered entire grains. The time reactions are not 

 carried beyond the 95 per cent of the total starch when this 

 is reached in 15 minutes, since this is considered as practically 

 the end of the reaction. The ungelatinized portion after this 

 period of time is generally very slowly affected, as determined 

 by an observation on several of the starches. In the group 

 /. cengialti-I. pallida queen of may-l. mrs. alan grey, the 

 observations up to 30 minutes are noted because the starch of 

 /. mrs. alan gray is comparatively slow; after 30 minutes the 

 gelatinization in this starch is very slow.) 



The reaction with potassium sulphide begins in 30 

 seconds. Complete gelatinization occurs in less than 0.5 

 per cent of the entire number of grains and 2 per ceirl 

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

 the grains and 6 per cent of the total starch in 15 min- 

 utes; in about 2 per cent of the grains and 10 per cent 

 of the total starch in 30 minutes; little if any further 

 advance in 45 and 60 minutes. (Chart D 430.) 



The reaction with sodium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 25 per 

 cent of the entire number of grains and 58 per cent of 

 the total starch in 2 minutes; in about 41 per cent of 

 the grains and 75 per cent of the total starch in 5 min- 

 utes ; in about 61 per cent of the gTains and 90 per cent 

 of the total starch in 15 minutes; in about 75 per cent 

 of the grains and 95 per cent of the total starch in 30 

 minutes; in about 78 per cent of the grains and 95 per 

 cent of the total starch in 45 minutes ; little if any fur- 

 ther advance in 60 minutes. (Chart D 431.) 



The hilum becomes distinct in all the grains. The 

 lamella? also are very distinct. Two fissures which pre- 

 exist in the untreated grain become more distinct and 

 are clearly seen to extend from the hilum to the distal 

 margin. The starch comprehended between them is 

 divided by many fine fissures into a number of fine 

 refractive granules. Gelatinization begins, usually, at 

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

 two processes approach one another; the most resistant 

 part of this portion of the grain being a row of rather 

 coarse granules, situated at about half the distance from 

 the hilum to the distal margin. The portion at the 

 proximal margin and sides meanwhile forms a homo- 

 geneous-looking refractive band at the margin which 

 gradually grows thinner and more nearly transparent 

 until it is completely gelatinized and only the capsule 

 remains. 



The gelatinized grains are much swollen, have moder- 

 ately thick capsules, and are considerably distorted espe- 

 cially at the distal end. 



Comparison of the sodium-hydroxide reactions be- 

 tween I. cengialti and I. pallida queen of may shows : 



The hilum and lamella are somewhat more distinct 

 than in /. pallida queen of may. Gelatinization usually 

 begins at the distal end and then at the proximal as in 

 7. pallida queen of may ; but in a number of grains it 

 begins at the hilum and proceeds to the distal end. 

 The starch comprehended between the 2 pre-existing 

 fissures which extend from the hilum to the distal end 

 is divided into finer granules than in I. pallida queen of 

 may and these are often arranged in rows corresponding 

 to the rows of lamella?, instead of irregularly as in 7. 

 pallida queen of may. 



