580 



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



total starch in 30 minutes; in about 16 per cent of the 

 grains and 20 per cent of the total starch in 45 minutes ; 

 and in about 18 per cent of the grains and 23 per cent 

 of the total starch in 60 minutes. (Chart D 329.) 



The hilum becomes distinct, accompanied by the 

 formation of rather large bubbles in very few grains. 

 The lamellae are no^ visible in most of the grains, but 

 in a few become moderately distinct. The grains be- 

 come considerably more refractive after the addition of 

 the reagent, and the first part of the grains to be so 

 affected is a broad band of material at the margin. 

 Gelatinization begins at 2, 3, or 4 discrete points on the 

 distal margin and progresses according to two methods. 

 In the first, which is seen in the great majority of the 

 grains, which are also the more resistant, gelatinization 

 proceeds from the initial points around the margin until 

 all the marginal starch is gelatinized, except a nar- 

 row strip at the proximal end. Then it progresses in- 

 ward preceded by irregular cracks and fissures which split 

 off particles of ungelatinized material, until the main 

 portion of the ungelatinized grain assumes an angular 

 instead of a rounded appearance. The proximal de- 

 posit is usually gelatinized before the portion of the 

 grain immediately surrounding the hilum, which when 

 the rest of the grain has been gelatinized is split into 

 two portions which are widely separated, and gelatinize 

 independently of one another. If a bubble is present 

 at the hilum when this splitting occurs it first swells, then 

 shrinks, and disappears. In the second method which 

 occurs in rather a small minority of the grains which 

 are also the less resistant, gelatiuization begins at the 

 distal end and then at the proximal end, and advances 

 smoothly from these two points. The last portion of the 

 grain to be gelatinized is that immediately distal to the 

 hilum, and this, just before gelatinization occurs, is 

 sometimes split into two portions which are widely separ- 

 ated, and gelatinize independently of one another. The 

 gelatinized grains are much swollen have rather thick 

 capsules and are considerably distorted. 



Comparison of the chloral-hydrate reaction between 

 N. madame de graaff and N. monarch shows : 



A bubble is formed at the hilum in more grains than 

 in N. monarch. The lamellae are visible in many more 

 grains and are moderately distinct when they are visible, 

 as in 2V. monarch. The grains do not become so refrac- 

 tive after the addition of the reagent. Gelatinization 

 progresses according to two methods, which are in gen- 

 eral the same as those described under N. monarch. In 

 the first method, which is seen in a smaller majority 

 of the grains than in N. monarch, the points of difference 

 to be noted are that the whole margin up to a narrow 

 strip at the proximal end is not gelatinized, but only the 

 distal margin, and the progress of gelatinization toward 

 the hilum is accompanied by the serial separation of 

 groups of lamellae, and the material at the proximal end 

 is the last portion of the grains to be gelatinized instead 

 of that just distal to the hilum. No differences are noted 

 in the second method. 



The gelatinized grains are more swollen, do not have 

 such thick capsules, and are more distorted than in 

 N. monarch. 



The reaction with chromic acid begins in 30 seconds. 

 Complete gelatinization occurs in less than 0.5 per cent 

 of the entire number of grains and 33 per cent of the 



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

 grains and 71 per cent of the total starch in 15 minutes; 

 in about 66 per cent of the grains and 95 per cent of the 

 total starch in 30 minutes; in about 90 per cent of the 

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

 in 45 minutes; and in about 95 per cent of the grains 

 and in more than 99 per cent of the total starch in 60 

 minutes. (Chart D 330.) (See footnote, page 516.) 



The hilum becomes distinct, unattended by the for- 

 mation of a bubble. The lamellae are at first not very 

 distinct, but later become distinct. Evidences of a lamel- 

 lar structure do not persist until near the end of the 

 reaction, as in some of the starches studied. Gelatiniza- 

 tion begins at the hilum and progresses according to two 

 methods. In the first, which is seen in a majority of 

 the grains, the portion of the grain immediately sur- 

 rounding the hilum and which in some grains can be 

 clearly seen to be a primary starch formation, is cracked 

 into 3 to 5 pieces, which are in turn subdivided into 

 8 or 9 more smaller portions. The secondary starch is 

 covered with rather fine striae, and as the less resistant 

 part is gelatinized and the grain swells, the more resis- 

 tant portion forms a rather finely striated marginal band 

 which at first sometimes shows a lamellar structure; 

 but which as gelatinization goes on becomes thinner and 

 more and more homogeneous in appearance. The par- 

 ticles of the primary starch are scattered irregularly 

 in the interior of the grain and often some remain un- 

 gelatinized until after solution begins. The distal por- 

 tion of the marginal band is often gelatinized and dis- 

 solved before gelatinization of the proximal end. In the 

 second method, which is seen in a minority of the grains, 

 two furrows or fissures extend transversely or obliquely 

 from the hilum on either side to the margin and the 

 material distal to them and to the hilum is divided 

 into very fine granules, and this granular mass in turn is 

 divided very irregularly by branching longitudinal fis- 

 sures from the hilum. As this portion of the grain is 

 slowly gelatinized with considerable swelling of the 

 grain, the proximal material, which has been divided by 

 rather fine striae, forms a striated band at the proximal 

 end, which is not gelatinized until after the distal portion. 

 The capsule at the distal end is often dissolved before 

 gelatinization is complete, and the contents of the 

 capsule flow out and are dissolved, the proximal ma- 

 terial being the last. About half the grains are dissolved 

 before gelatinization is complete. The gelatinized grains 

 are much swollen, have thin capsules, and are not greatly 

 distorted. 



Comparison of the chromic-acid reaction between 

 N. madame de graaff and N. monarch shows : 



The hilum and lamellae are as distinct as in N. mon- 

 arch. Gelatinization progresses according to two 

 methods, which are very similar to the two described 

 under N. monarch. The first is seen in a larger ma- 

 jority of the grains than in N. monarch, and the differ- 

 ences noted are that the primary deposit is more apt 

 after division to remain clumped in the interior of the 

 grain, and the strife which divide the secondary starch 

 are not so fine and are more distinct than in N. monarch. 

 In the second method, which is seen in a smaller minor- 

 ity of the grains than in N. monarch, there are no im- 

 portant differences, except that the material distal to the 



