574 



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



denly arid the bubble if present swells, shrinks, and 

 disappears. The proximal starch becomes hyaline in 

 appearance and then is rapidly gelatinized. 



The gelatinized grains are much swollen, have thick 

 capsules, and are much distorted. 



Comparison of the chloral-hydrate reaction between 

 N. madame de graaff and N. weardale perfection shows : 



A small bubble is less frequently formed at the 

 hilum than in N. weardale perfection. The lamellae are 

 at first not visible, but later become moderately distinct 

 in many more grains than in N. weardale perfection. 

 The grains become somewhat more refractive in appear- 

 ance after the addition of the reagent than in that 

 starch. Gelatinization progresses according to the two 

 methods described under N. iveardale perfection. In the 

 first, which is observed in a majority of the grains and 

 which is very nearly the same as that seen in an even 

 greater majority of the grains of N. weardale perfection, 

 the main differences noted are that gelatinization does 

 not progress around the margin so close to the proxi- 

 mal end, and there is not so much splitting of the grain 

 by fissures or serial separation of groups of lamellae 

 as in N. weardale perfection. In the second method, 

 which is seen in a minority of the grains as in N. wear- 

 dale perfection, the only difference noted is that gela- 

 tinization begins at both distal and proximal ends, in- 

 stead of only at the distal end. The gelatinized grains 

 are more swollen, do not have such thick capsules, and 

 are more distorted than in N. weardale perfection. 



The reaction with chromic acid begins in 1 minute. 

 Complete gelatinization occurs in about 0.5 per cent of 

 the entire number of grains and 5 per cent of the total 

 starch in 5 minutes; in about 2 per cent of the grains 

 and 40 per cent of the total starch in 15 minutes; in 

 about 4U per cent of the grains and 91 per cent of the 

 total starch in 30 minutes; in about 91 per cent of the 

 grains and 99 per cent of the total starch in 45 minutes ; 

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

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

 D :^4.) (See footnote, page 516.) 



The hilum becomes distinct, unattended by the for- 

 mation of a bubble. The lamellas at first are moderately 

 distinct, but later become very distinct, and traces of a 

 lamellar structure are seen when gelatiuization is nearly 

 complete. Gelatinization begins at the hilum and pro- 

 gresses according to two methods. In the first, which 

 is seen in a small majority of the grains, the portion 

 of the grain immediately around the hilum which is not 

 always distinguishable as primary starch is divided into 

 four or five portions by fissures, and these portions are 

 subdivided into rather coarse granules. The rest of the 

 grain is divided by rather fine stria? which gradually 

 grow coarse and very distinct. As the less resistant part 

 of the grain gelatinizes and swells, the more resistant 

 portion forms a coarsely striated and lamellated band at 

 the margin, while the granular material around the 

 hilum is scattered throughout the interior of the grain. 

 The marginal band is often divided by fissures at the 

 proximal and the distal ends, and these portions are 

 gelatinized more rapidly than the rest. The remaining 

 parts become gradually thinner and more homogeneous- 

 looking ; finally they are gelatinized and only the capsule 

 is left. Meanwhile the granules in the interior of the 

 grain have been gradually growing smaller and more 



refractive, but some of them persist after the rest of 

 the grain is completely gelatinized and then disappear 

 very gradually. In the second method 2 furrows or fis- 

 sures extend from the hilum on either side to the margin 

 and the starch distal to these furrowa and to the hilum 

 is fissured and divided into granules which are rather 

 coarse near the hilum and fine in the rest of the grain ; 

 only a small rim of marginal starch is left unfissured. 

 This, in connection with a thicker portion at the proximal 

 end, becomes coarsely striated and is the last portion of 

 the grain to be gelatinized. The granular distal material 

 is divided by radiating longitudinal fissures from the 

 hilum and is slowly gelatinized, with considerable swell- 

 ing of the grain. The starch at the margin is gela- 

 tinized even more slowly, first at the distal and then at 

 the proximal end. 



The grains are nearly always completely gelatinized 

 before they are dissolved. The gelatinized grains are 

 much swollen, have rather thin capsules, and are not 

 much distorted. 



Comparison of the chromic-acid reactions between 

 N. madame de graaff and N. weardale perfection shows: 



The hilum and lamella? are as distinct as in N. wear- 

 dale perfection. Gelatinization progresses according to 

 two methods, which are in general the same as those de- 

 scribed under N. weardale perfection. The first, which 

 is found in a large majority of the grains, is that which 

 is seen in a small majority of the grains of N. weardale 

 perfection. The only differences noted are that there 

 is usually a clear distinction between the primary and 

 the secondary starch ; and the granules formed from the 

 primary starch are coarser and more refractive and some- 

 times remain clumped together in the center of the grain, 

 while the secondary starch is being gelatinized and the 

 grain is swelling. When they do so they are not gela- 

 tinized until after the grain has begun to dissolve. In 

 the second method, which is seen in a small minority 

 of these grains and a large minority of those of N. wear- 

 dale perfection, the only difference is that the marginal 

 material at the proximal end only instead of all around 

 the margin forms a resistant baud which is gelatinized 

 more slowly than the rest of the grain. Some of the 

 grains are dissolved before gelatinization is complete. 

 The gelatinized grains are more swollen and have thinner 

 capsules, but are no more distorted than in N. weardale 

 perfection. 



The reaction with pyrogallic acid begins in 2 min- 

 utes. Complete gelatiuization occurs in less than 0.5 

 per cent of the entire number of grains and 3 per cent 

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

 of the grains and 37 per cent of the total starch in 15 

 minutes; in about 54 per cent of the grains and 79 per 

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

 cent of the grains and 86 per cent of the total starch 

 in 45 minutes ; and in about 70 per cent of the grains and 

 91 per cent of the total starch in 60 minutes. (Charts 

 D325 and D326.) 



The hilum becomes distinct, unaccompanied by the 

 formation of a bubble. The lamella? are distinct in all 

 the grains and remain so during the greater part of the 

 reaction. Gelatinizatiou begins at the hilum and pro- 

 ceeds according to two methods. In the first method, 

 which is seen in a small majority of the grains, the 

 starch immediately surrounding the hilum is divided 



