666 



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



dividing the grain into rows of rather fine granules, 

 arranged in the manner of the lamellae. As enlargement 

 of both hilum and grain continues, the less resistant 

 starch is gelatinized and the more resistant portion 

 forms a lamellated granular band at the margin, which 

 remains lamellated and granular until very late in the 

 reaction, becoming thinner and more nearly transpar- 

 ent, more quickly at the distal end (or what may be 

 considered the distal end) than at the proximal end and 

 sides, until finally only the thin capsule remains. In 

 some of these grains, the starch around the hilum, at 

 the beginning of the reaction, is divided into rather 

 coarse granules which are very resistant, and which as 

 the reaction progresses are pushed to the inner border of 

 the marginal band before described, and remains there, 

 becoming gradually smaller and more refractive long 

 after the rest of the material of the grain has been gela- 

 tinized, until, finally, they too are gelatinized. In the 

 second type of procedure, which occurs in a rather small 

 number of grains, which are somewhat elongated in form, 

 2 refractive fissures, which are often already present in 

 the untreated grain, run from the hilum to the distal 

 margin, branching out as they near the margin. The 

 starch comprehended between them becomes more re- 

 fractive and is divided into granules, and this portion 

 of the grain is more rapidly gelatinized than the material 

 at the proximal end and sides, which forms a densely 

 striated, lamellated, marginal band, and this gradually 

 becomes thinner and more nearly transparent until only 

 the thin capsule is left. 



The gelatinized grains are usually considerably swol- 

 len, rather thin walled, and not much distorted especially 

 at the proximal end. There is not much dissolution of the 

 capsule except after complete gelatinization has occurred. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 44 per 

 cent of the entire number of grains and 80 per cent of 

 the total starch in 5 minutes; in about 68 per cent of 

 the grains and 98 per cent of the total starch in 15 min- 

 utes ; in about 72 per cent of the grains and 99 per cent 

 of the total starch in 30 minutes. (Chart D 448.) A 

 delicate, complete, or partial layer of starch at the 

 margin of a small percentage of the grains is quite 

 resistant. 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 77 per 

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

 in 5 minutes; in 96 per cent of the total starch in 10 

 minutes; in about 93 per cent of the grains and 99 per 

 cent of the total starch in 15 minutes. (Chart D 449.) 



The hilum is very distinct, and a large bubble is often 

 formed there. The lamellae are not distinct, and some- 

 times can not be distinguished. Gelatinization begins 

 at the hilum, which in the great majority of the grains 

 enlarges somewhat, and rather coarse striae appear which 

 radiate from the hilum throughout the grain to the 

 margin. If fissures are present in the untreated grain, 

 these enlarge and extend further into the substance of the 

 grain. The bubble, which was large, shrinks and dis- 

 appears, and the hilum and the whole grain begin to 

 enlarge steadily and with moderate rapidity. The more 

 resistant starch is pushed to the margin where it forms 

 a striated band which soon becomes granular and, as the 

 reaction proceeds, this granular band gradually becomes 



thinner and more nearly transparent, and more homo- 

 geneous in appearance, until finally only the thin capsule 

 is left. In some of the elongated grains in which 2 refrac- 

 tive fissures proceeding from the hilum exist in the un- 

 treated grain, the fissures become more extensive, and 

 branching toward the distal end, and the part of the 

 grain included between them and the hilum and the 

 distal margin becomes more refractive in appearance and 

 then is divided into many granules. The proximal end is, 

 however, nearly always the first to be gelatinized, and 

 there is always a striated, lamellated band around the 

 entire margin, and, after the rest of the grain is com- 

 pletely gelatinized, there is often a collection of rather 

 coarse, refractive granules at the distal margin which 

 are very resistant and remain for some time ungelatinized. 



The gelatinized grains are much swollen, and have 

 rather thick capsules, but are much distorted and do not 

 retain much resemblance to the form of the untreated 

 grain. 



The reaction with potassium sulphacyanate begins 

 immediately. Complete gelatinization occurs in about 

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

 cent of the total starch in 2 minutes; in about 90 per 

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

 total starch in 5 minutes. (Chart D 450.) 



The reaction with potassium sulphide begins imme- 

 diately. Complete gelatinization occurs in about 3 per 

 cent of the entire number of grains and 11 per cent of 

 the total starch in 5 minutes ; in about 4 per cent of the 

 grains and 14 per cent of the total starch in 15 minutes; 

 in about 5 per cent of the grains and 20 per cent of the 

 total starch in 30 minutes ; in about the same percentage 

 of the grains and 21 per cent of the total starch in 45 and 

 60 minutes. (Chart D 451.) 



The reaction with sodium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 66 per 

 cent of the entire number of grains and 92 per cent of 

 the total starch in 2 minutes; in about 95 per cent of the 

 total starch in 3 minutes; and in about 92 per cent of 

 the grains and in more than 99 per cent of the total 

 starch in 5 minutes. (Chart D452.) 



The hilum becomes very distinct, and a bubble is 

 apparently never formed there. In a few grains, 2 

 refractive fissures, which extend from the hilum nearly 

 to the distal margin, and are present before the addition 

 of the reagent, become more prominent, more extensive, 

 and more branched. The lamellae are very distinct and 

 remain so during the greater part of the reaction. Gela- 

 tinization begins at the hilum, and in the majority of 

 the grains a few striae appear which radiate from the 

 hilum in all directions throughout the grain to the 

 margin. The hilum enlarges equally in all directions, 

 and the whole grain slowly swells, the more resistant 

 starch forming a striated, lamellated band around the 

 margin. Later this band is divided into rows of gran- 

 ules which retain the lamellated appearance for a long 

 time. As reaction proceeds the granules become progres- 

 sively thinner and more nearly transparent until they 

 disappear and only the thin capsule is left. In some 

 grains in addition to this formation of granules at the 

 margin, irregular and refractive granules are formed of 

 the portion immediately surrounding the hilum, and 

 these, as swelling proceeds, are scattered rather irregu- 

 larly through the grain and prove to be the most resistant 





