IRIS. 



G49 



TEMPERATURE REACTIONS. 



The temperature of gelatinization of the majority of 

 the grains is 70 to 72 C., and of all is 74 to 76 C., 

 mean 75 C. 



Comparison of the temperature reactions between 

 I. iberica and /. cengialti shows : 



The temperature of gelatinization of all the grains is 

 71 to 72.5 C.,mean 71.8 C., 3.2 C. less than thatof the 

 grains of /. cengialti. 



EFFECTS OF VARIOUS REAGENTS. 



The reaction with chloral hydrate begins in 1 min- 

 ute. Complete gelatinization occurs in about 4 per cent 

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

 total starch in 5 minutes; in about 24 per cent of the 

 grains and 34 per cent of the total starch in 15 minutes; 

 in about 43 per cent of the grains and 52 per cent of 

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

 the grains and 62 per cent of the total starch in 45 min- 

 utes ; in about 62 per cent of the grains and 66 per cent 

 of the total starch in 60 minutes. (Chart D 400.) 



The hilum becomes distinct, attended by the forma- 

 tion of a comparatively large bubble in most grains. The 

 lamellae are rather indistinct and are obliterated as 

 gelatiuization progresses. The grains become more re- 

 fractive in appearance after the addition of the reagent, 

 and the first portion of the grain to show this is a rather 

 narrow band of material around the margin. Gela- 

 tinization begins at the corners of the distal margin and 

 progresses smoothly toward the hilum and proximal end 

 preceded by a pitted appearance in the ungelatinized 

 material. It progresses usually with equal rapidity in 

 the center and at the margins of the grains; but some- 

 times the interior of a grain is much less resistant than 

 the margin, and gelatinization proceeds rapidly to the 

 hilum in the interior of the grain, leaving the marginal 

 material to be gelatinized later. The most resistant part 

 of the grain and the last part to be gelatinized is always 

 the proximal end. The gelatinized grains are large and 

 have rather thick capsules, and are usually not very 

 much distorted. 



Comparison of the chloral-hydrate reactions between 

 /. iberica and /. cengialti shows : 



A bubble is formed as frequently as in I. cengialti, 

 but is usually larger than in that starch. The lamellae 

 are also indistinct. The first part of the grain to be- 

 come refractive after the addition of the reagent is a 

 less narrow band of starch at the margin which is, 

 however, not so refractive as the narrower band in I. cen- 

 giaUi. Gelatinization begins at the corners of the distal 

 margin, but is preceded at these points by fissures which 

 separate this portion from the rest of the grain. These 

 are not seen in 7. cengialti. The rest of the distal deposit 

 assumes a pitted appearance and is invaded on either 

 side by a longitudinal refractive fissure which extends 

 about two-thirds of the way from the distal to the proxi- 

 mal end. Between these 2 fissures the starch becomes 

 more and more refractive, is invaded by several longi- 

 tudinal, refractive fissures, and is finally divided into 

 granules of varying size and shape. In the meantime 

 gelatinization spreads from the corners of the distal 

 end along the distal margin and now spreads toward 

 the proximal end. A similar process is never seen in 

 7. cengialti. Gelatinization proceeds more rapidly in 

 18 



the interior than elsewhere, instead of with equal rapid- 

 ity in both interior and margin as in most of the grains 

 of I. iberica. 



The gelatinized grains are as much swollen, have 

 thin instead of rather thick capsules, and are very much 

 more distorted than in 7. cengialti. 



The reaction with chromic acid begins in 1 minute. 

 Complete gelatinization occurs in less than 0.5 per cent 

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

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

 grains and 63 per cent of the total starch in 15 minutes; 

 in about 41 per cent of the grains and 90 per cent of the 

 total starch in 30 minutes ; in about 45 per cent of the 

 grains and 95 per cent of the total starch in 45 minutes; 

 in about 90 per cent of the grains and in more than 99 

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

 D401.) 



The reaction with pyrogallic acid begins in 30 sec- 

 onds. Complete gelatinization occurs in less than 0.5 

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

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

 grains and 45 per cent of the total starch in 15 minutes ; 

 in about 19 per cent of the grains and 71 per cent of 

 the total starch in 30 minutes; in about 25 per cent of 

 the grains and 78 per cent of the total starch in 45 

 minutes ; in about 35 per cent of the grains and 84 per 

 cent of the total starch in 60 minutes. (Chart D 402.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in less than 0.5 per cent 

 of the entire number of grains and 12 per cent of the 

 total starch in 5 minutes; in about 13 per cent of the 

 grains and 66 per cent of the total starch in 15 minutes; 

 in about 23 per cent of the grains and 73 per cent of the 

 total starch in 30 minutes ; in about 27 per cent of the 

 grains and 83 per cent of the total starch in 45 minutes ; 

 in about 40 per cent of the grains and 90 per cent of 

 the total starch in 60 minutes. (Chart D403.) 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 64 per cent of 

 the entire number of grains and 89 per cent of the total 

 starch in 2 minutes ; in about 93 per cent of the grains 

 and 99 per cent of the total starch in 5 minutes. (Chart 

 D404.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 20 per 

 cent of the entire number of grains and 60 per cent of 

 the total starch in 5 minutes ; in about 38 per cent of the 

 grains and 82 per cent of the total starch in 15 minutes; 

 in about 48 per cent of the grains and 90 per cent of the 

 total starch in 30 minutes ; in about the same percentage 

 of the grains and total starch in 45 minutes ; in about the 

 same percentage of the grains and 92 per cent of the 

 total starch in 60 minutes. (Chart D 405.) 



The hilum becomes very distinct, unattended by the 

 formation of a bubble in any of the grains. The lamellse 

 are very distinct. Gelatinization begins at the hilum 

 which swells slightly. Two extensively branching fis- 

 sures extend from either side of the hilum nearly to the 

 distal margin. The branches from these fissures divide 

 the starch comprehended between them into many rather 

 coarse refractive granules. From this point onward 

 gelatinization progresses according to two methods. In 

 the first method, which is seen in a majority of the 

 grains, gelatiuization begins at the distal margin and 



