650 



DATA OF PROPERTIES OF STARCHES OF PARENT- AND HYBRID-STOCKS. 



then at the hilum and advances from these two points. 

 The most resistant portion of the grain is usually a row 

 of coarse granules which occur at a point one-half to 

 two-thirds of the distance from the hilum to the distal 

 margin, and less often just distal to the hilum. In 

 the meantime the portion at the proximal end and sides 

 nearby forms a lamellated and striated marginal band 

 which presents a fringed appearance on its inner border 

 due to its division into narrow spicules. This band grows 

 progressively thinner and more nearly transparent and is 

 finally gelatinized. The granules formed from the distal 

 deposit as already described are usually the last part 

 of the grain to be gelatinized and persist often for a long 

 time. In the second method which is seen in a large 

 minority of the grains, after the division of the distal 

 material into granules gelatinization begins at the hilum 

 which swells, and the distal portion begins to gelatinize 

 from the hilum toward the distal end. Before the distal 

 end is reached it is invaded at the margin by several 

 longitudinal fissures which divide the starch and appar- 

 ently hasten gelatinization. In the meantime the more 

 resistant material at the proximal end and sides nearby 

 forms a thick, indistinctly striated and lamellated mar- 

 ginal band around the inner border of which a num- 

 ber of granules formed from the starch immediately sur- 

 rounding the hilum are arranged. This band becomes 

 progressively thinner and more nearly transparent and 

 is finally also gelatinized; the proximal margin being 

 the last, except for the resistant granules scattered around 

 the inner border, to be gelatinized. 



The gelatinized grains are much swollen, have thin 

 capsules, and are not greatly distorted. A few grains 

 show partial or complete solution before gelatinization 

 is complete. 



Comparison of the hydrochloric-acid reactions be- 

 tween I. iherica and I. cengialti shows : 



The hilum and lamella? are not so distinct as in I. 

 cengialti. Gelatinization in all the grains proceeds 

 according to the method described for a moderate minor- 

 ity of the grains of I. cengialti. The only difference to 

 be noted is that the material distal to the hilum and 

 comprehended between the 2 fissures which proceed from 

 either side of the hilum is divided into much finer and 

 less refractive granules than in I. cengialti. 



The gelatinized grains are as much swollen, and do 

 not have such thin capsules as in I. cengialti. They are, 

 however, somewhat more distorted than in that starch. 

 There are more grains in which dissolution of the capsule 

 at one point and partial or complete solution of the grain 

 occurs than in I. cengialti. 



The reaction with potassium hydroxide begins im- 

 mediately. Complete gelatinization occurs in about 20 

 per cent of the entire number of grains and 75 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 50 per cent of the grains and 90 per 

 cent of the total starch in 30 minutes; in about 56 per 

 cent of the grains and 93 per cent of the total starch in 

 45 minutes; in about 60 per cent of the grains and 94 

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

 D406.) 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 14 per 

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



the total starch in 5 minutes ; in about 41 per cent of the 

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

 in about 50 per cent of the grains and 86 per cent of the 

 total starch in 30 minutes; in about 66 per cent of the 

 grains and 91 per cent of the total starch in 45 minutes; 

 in about 66 per cent of the grains and 93 per cent of the 

 total starch in 60 minutes. (Chart D 407.) 



The hilum becomes very distinct, unattended by the 

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

 also become very distinct and evidences of a lamellar 

 structure remain visible throughout a greater part of the 

 reaction. Gelatinization begins at the hilum, which 

 enlarges slightly, and 2 fissures which are pre-existent 

 in the untreated grain become very prominent and are 

 seen to extend from either side of the hilum nearly 

 to the distal margin. The starch which is included 

 between these fissures becomes more refractive, and is 

 divided into rather coarse, refractive granules by a 

 number of fissures. The starch at the distal margin is 

 then invaded by many longitudinal fissures and rapidly 

 gelatinized. This is followed by gelatinization imme- 

 diately distal to the hilum, and the two processes ap- 

 proach one another, a band of coarse granules midway 

 between the hilum and the distal margin being the last of 

 this portion of the grain to be gelatinized. The most 

 resistant portion of the grain is usually formed at the 

 proximal end and sides. This forms a striated and 

 lamellated marginal band, which as the grain continues 

 to swell, is gradually gelatinized, and loses its striated 

 appearance, but retains some of its lamellated appear- 

 ance until it is nearly completely gelatinized. In a few 

 grains the proximal end is gelatinized immediately after 

 the distal end, and the most resistant part of the grain is 

 that midway between the hilum and the distal end. 



The gelatinized grains are much swollen, have rather 

 thick capsules, and are usually somewhat distorted. 



Comparison of the potassium-iodide reactions be- 

 tween I. iherica and I. cengialti shows : 



The hilum and lamella? are not so distinct as in 

 7. cengialti. Gelatinization proceeds in much the same 

 manner as in I. cengialti, the differences noted being that 

 the granules into which the portion of the grains in- 

 cluded betewen the 2 pre-existing fissures is divided, are 

 not so large and less refractive; the lamellated appear- 

 ance does not remain so long visible in the marginal 

 band at the proximal end and sides, and tins band is 

 distinctly striated, and there are fewer grains in which 

 gelatinization begins first at the proximal end and sub- 

 sequently at the distal end, than in I. cengialti. The 

 gelatinized grains are as much swollen, but have thin 

 instead of rather thick capsules, and are somewhat more 

 distorted than in I. cengialti. 



The reaction with potassium sulphocyanate begins 

 immediately. Complete gelatinization occurs in about 

 39 per cent of the entire number of grains and 81 per 

 cent of the total starch in 2 minutes; in about 66 per 

 cent of the grains and 91 per cent of the total starch 

 in 5 minutes; in about 72 per cent of the grains and 95 

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

 cent of the grains and 98 per cent of the total starch in 

 30 minutes. (Chart D408.) 



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 3 per cent of 



