738 



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



distal end is usually more distorted than the proximal 

 end. The gelatinized grains do not resemble the un- 

 treated grain. 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 78 per cent of 

 the entire number of grains and 93 per cent of the total 

 starch in 1 minute; in about 95 per cent of the entire 

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

 2 minutes; complete gelatinization (100 per cent) in 3 

 minutes. (Chart D 578.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 84 per 

 cent of the entire number of grains and 96 per cent of 

 the total starch in 1 minute ; in about 92 per cent of the 

 grains and over 99 per cent of the total starch in 2 

 minutes ; these resistant parts gradually gelatinize in 3 

 and 4 minutes, complete gelatinization of all grains occur- 

 ring in 5 minutes. (Chart D 579.) 



The hilum becomes very distinct, attended by the 

 formation of a bubble. The lamellae appear very dis- 

 tinct. A very refractive band is formed about the mar- 

 gin, which is broad at the proximal end, and narrow at 

 the distal, and in some grains is not visible. Gelatiniza- 

 tion begins at the hilum which enlarges, the bubble 

 shrinks and disappears, and the starch immediately sur- 

 rounding it is divided into a number of coarse granules. 

 The proximal starch, with the exception of the granules, 

 is rapidly gelatinized and the proximal end of the grain 

 swells suddenly. The rest of the grain is divided by fine 

 radiating striae, which later develop into fine fissures, 

 into granules arranged in rows according to the lamellar 

 structure, and as gelatinization proceeds they are pushed 

 to the distal margin and there gelatinized. The gran- 

 ules at the proximal end persist long after the rest of the 

 grain is gelatinized, but are finally also gelatinized. The 

 gelatinized grains are large and very nearly transparent 

 and very thin-walled, but retain some of the form of the 

 untreated grain. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 90 per 

 cent of the entire number of grains and 93 per cent of the 

 total starch in 15 seconds; in about 95 per cent of the 

 grains and 98 per cent of the total starch in 30 seconds ; 

 in about 97 per cent of the grains and over 99 per cent 

 of the total starch in 1 minute. ( Chart D 580. ) 



The hilum becomes very distinct, a bubble is not 

 formed there. The lamellae also become very distinct and 

 appear so as long as there is any trace remaining of the 

 structure of the untreated grain A narrow, refractive 

 band forms very rapidly about the margin, and the starch 

 constituting this is not gelatinized until all the rest of 

 the grain is gelatinized. Gelatinization begins at the 

 hilum, and immediately afterward at the distal margin. 

 From this point there are two methods of progress. In 

 the first, the starch immediately surrounding the hilum 

 is broken up into granules which persist for some time 

 after the rest of the grain, except that the border before 

 mentioned is gelatinized, then the hilum enlarges rap- 

 idly, pushing out the proximal end; then gelatinization 

 proceeds toward the distal end, the starch just inside 

 the refractive border being much the less resistant, it pro- 

 gresses more rapidly in it than in the central portion of 

 the grain, producing a ruffled appearance of the border; 

 in the meantime gelatinization has been progressing 

 less rapidly from the distal end, one lamella after an- 



other being gelatinized and thus giving rise to a folded 

 appearance of the capsule at this end. Finally, all the 

 starch is gelatinized except the refractive border which 

 persists for some time, but gradually grows thinner and 

 more nearly transparent, until only a thin capsule is left. 

 In the second method, after the beginning at the hilum 

 and the distal corners, the progress is almost entirely 

 from the proximal end, granules are rarely formed about 

 the hilum, and progress toward the distal end is uni- 

 form in all parts. Usually the starch before gelatiniza- 

 tion is divided into rows of granules, following the 

 lamellar arrangement by several fissures. A similar 

 refractive border to that noted in the first method is 

 present and this persists after the rest of the grain has 

 been gelatinized, then grows thinner and more trans- 

 parent as already described. The gelatinized grains are 

 large and usually considerably distorted, especially at 

 the distal end, but they retain considerable of the form 

 of the untreated grain. 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 27 per 

 cent of the entire number of grains and 68 per cent of the 

 total starch in 5 minutes; in about 61 per cent of the 

 grains and 90 per cent of the total starch in 15 minutes ; 

 in about 80 per cent of the grains and 95 per cent of the 

 total starch in 30 minutes ; in about 87 per cent of the 

 grains and 97 per cent of the total starch in 45 minutes ; 

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

 total starch in 60 minutes. (Chart D 581.) 



The moderately small grains are the most resistant. 

 A small bubble occasionally appears at the hilum, and 

 there is distention of the capsule as a small swelling forms 

 in a number of grains; but in the majority the hilum 

 swells and gelatinization proceeds first from this point 

 towards the distal margin, a refractive marginal band 

 of lamellae at the proximal end and sides being the most 

 resistant. The lamellae quickly appear to be more sharply 

 defined and striated, with the exception generally of the 

 narrow refractive band above mentioned, in which the 

 lamellae may gradually become distinct. Two deep, 

 clean-cut fissures usually proceed from the hilum and 

 are directed obliquely towards the distal corners, forming 

 a sharp boundary between the refractive bilateral border 

 and the mesial portion of the grain ; in some grains one 

 median, broad fissure with short branches may proceed 

 through the region of the hilum and then become bifur- 

 cated and clean-cut as above mentioned. Occasionally a 

 group of delicate fissures may leave the hilum between the 

 2 main fissures, or delicate branched fissures may form 

 in the median portion starting from the area nearer the 

 proximal end, which has been gelatinized. The mesial 

 portion is usually broken into moderate to very refractive 

 granules, the latter being in groups, one of which may 

 be located in the area at the hilum, this group being 

 either round or oval and larger than the remainder of the 

 groups. The lamellae toward the distal margin are often 

 broken down into linear granules, although gelatinization 

 may follow the sharper definition and striation without 

 breaking into granules. The refractive marginal band 

 at the proximal end and sides is very resistant with the 

 exception sometimes of a small area at the proximal end, 

 which frequently may gelatinize without breaking into 

 linear granules. 



The gelatinized grains are swollen and distorted, and 

 usually the portion near the distal margin, frequently 



