556 



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



A bubble is much less frequently f onned at the hilum, 

 and the lamellae are more often moderately distinct than 

 in N. abscissus. The grains become less refractive after 

 the addition of the reagent and the band of material 

 around the margin, which is the first part of the grain 

 to show this change, is narrower than in N. abscissus. 

 Gelatinization proceeds according to two methods neither 

 of which resembles closely the three methods noted in 

 N. abscissus. In the first method, which is somewhat 

 similar to the third method of N. abscissus, the marginal 

 starch is gelatinized nearly to the proximal end on 

 both sides and then proceeds inward, preceded by fissur- 

 ing of the ungelatinized portion and splitting off of par- 

 ticles of ungelatinized material. In the second method 

 gelatinization begins at several points on the margin 

 and proceeds from each of these points, forming deep, 

 cup-shaped hollows which finally coalesce before the 

 hilum and proximal end are reached. The gelatinized 

 grains are as much swollen and have thinner capsules 

 and are more distorted than those of N. abscissus. 



The reaction with chromic acid begins in 1 minute. 

 Complete gelatinization occurs in less than 0.5 per cent of 

 the entire number of grains and 4 per cent of the total 

 starch in 5 minutes ; in less than 0.5 per cent of the grains 

 and 26 per cent of the total starch in 15 minutes ; in about 

 12 per cent of the grains and 81 per cent of the total 

 starch in 30 minutes ; in about 46 per cent of the grains 

 and 95 per cent of the total starch in 45 minutes; and in 

 about 62 per cent of the grains and 98 per cent of the 

 total starch in 60 minutes. (Chart D 306.) (See foot- 

 note, page 516.) 



The hilum is distinct, and the lamellae are distinct 

 in all the grains. Gelatinization begins at the hilum and 

 progresses according to two methods. In the first, which 

 is seen in a great majority of the grains, the primary 

 starch is divided by fissures or cracks into a number of 

 particles. In most of the grains these particles are 

 again divided until the central part of the interior of the 

 large grain appears filled with a fine granular mass 

 which is the first part to be gelatinized. The secondary 

 starch meanwhile is coarsely striated, and as the finely 

 granular primary starch and the less resistant part of 

 the secondary starch are gelatinized and the grain swells, 

 the more resistant material forms a coarsely striated mar- 

 ginal band which is thinner in some places than in others. 

 This band gradually grows thinner and more nearly 

 transparent and is eventually dissolved at the points 

 where it is thinnest. In other grains the primary starch 

 is divided into rather large fragments which are very 

 resistant and are scattered around the inner border of 

 the marginal band formed of the secondary starch and 

 remain there until the capsule is dissolved in one or 

 two places and then flow out into the reagent and are 

 dissolved. In the second method, which is seen in only 

 a few of the grains, two furrows or actual fissures extend 

 from either side of the hilum nearly to the margin, 

 and distal to these furrows or fissures are a number of 

 other branching fissures which radiate out from the 

 hilum on either side like a bundle of wheat. The ma- 

 terial between the hilum, the furrows, and the margin 

 becomes finely granular, except a narrow band at the 

 margin, and is slowly gelatinized, while the radiating 

 fissures before described slowly widen and branch and 

 finally disappear. The proximal starch meanwhile is 



coarsely striated, and with the thin portion of material 

 already described, which is around the rest of the margin, 

 forms a striated band which slowly grows thinner and 

 then is dissolved in 1 or 2 places. The contents flow 

 out and are dissolved and the marginal portion slowly 

 dissolves also, the proximal portion being the most re- 

 sistant. The grains are always dissolved before gela- 

 tinization is complete. 



Comparison of the chromic-acid reactions between 

 N. poeficus poetarum and N. abscissus shows : 



The hilum is as distinct but the lamellae are not so 

 distinct as in N. abscissus. Gelatinization follows two 

 methods, one of which is very similar to the one de- 

 scribed under N. abscissus. In the first, which re- 

 sembles that described for a small minority of the grains 

 of N. abscissus, the main points of difference noted are 

 that the fissures which divide the grain distal to the 

 preliminary furrows from either side of the hilum are 

 finer and more numerous, and that the whole area be- 

 tween the furrows and the margin becomes finely granular 

 and is gelatinized, instead of a small band of material 

 at the margin remaining ungelatinized, as in N. abscissus. 

 In the second method there are several differences to be 

 noted between N. abscissus and N. poeticus poetarum. 

 There is no apparent distinction between primary and 

 secondary starch, but several fissures extend longitu- 

 dinally from the hilum to the distal margin, and this part 

 of the grain is gelatinized first and then the portion at 

 the proximal end and sides nearby is striated and slowly 

 gelatinized. The grains are frequently dissolved before 

 gelatinization is complete, but in some grains gelatiniza- 

 tion is complete and the gelatinized grains are much 

 swollen, have thin capsules, and are considerably 

 distorted. 



The reaction with pyrogallic acid begins in 1 minute. 

 Complete gelatinization occurs in about 1 per cent of 

 the entire number of grains and 23 per cent of the total 

 starch in 5 minutes; in about 25 per cent of the grains 

 and 66 per cent of the total starch in 15 minutes; in 

 about 46 per cent of the grains and 79 per cent of the 

 total starch in 30 minutes ; in about 62 per cent of the 

 grains and 88 per cent of the total starch in 45 minutes ; 

 and in about 71 per cent of the grains and 92 per cent 

 of total starch in 60 minutes. (Charts D 307, D 308.) 



The hilum is distinct; the lamellae are moderately 

 distinct, but do not remain so during the reaction. Gela- 

 tinization begins at the hilum and progresses according 

 to two methods. In the first, which is seen in the great 

 majority of the grains, the primary starch is split length- 

 wise into two pieces, which are in turn each divided into 

 two or three pieces. The secondary starch which sur- 

 rounds the primary starch is meanwhile marked by rather 

 fine striae. As the less resistant material of both primary 

 and secondary starch is gelatinized, causing swelling of 

 the whole grain, the more resistant part of the secondary 

 starch forms a finely striated marginal band, around 

 the inner border of which the subdivided particles of the 

 primary starch are scattered. The marginal band be- 

 comes more coarsely striated and develops a feathery or 

 spicular inner border and then gradually grows thinner 

 and more refractive and is finally gelatinized. The par- 

 ticles of the primary starch are very resistant and remain 

 for some time after the rest of the grain has been gela- 

 tinized. In the second method two furrows extend trans- 



