562 



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



The gelatinized grains are much swollen and have 

 rather thick capsules, they are very much distorted and 

 do not retain any resemblance to the form of the un- 

 treated grain. 



Comparison of the chloral-hydrate reactions between 

 .V. abscissas and iV. ulbiatns shows: 



A bubble is not formed at the hilum in so many 

 grains as in :Y. albicans, and the lamellae are not visible 

 in any of the grains. The marginal material, which 

 first shows an increased refractivity after the addition 

 of the reagent, is in a band which is not so broad as in 

 N. albicans. Gelatinization progresses according to three 

 methods instead of two, as in N. albicans. In the first, 

 which is seen in the majority of the grains and which was 

 not observed in A 7 , albicans, gelatiuization begins first at 

 the distal end, then at the proximal and progresses: from 

 these two points, the portion of the grain just distal to 

 the hilum being the last to be gelatinized. In the second 

 method, which somewhat resembles the second method de- 

 scribed under N. albicans, gelatinizatiou begins at the 

 distal margin and proceeds toward the hilum, accom- 

 panied by serial separation of groups of lamella;, which 

 is not seen in N. albicans. The proximal end is the last 

 portion gelatinized in such grains. The third method 

 is the same as that described for the majority of the 

 grains of N. albicans. 



The gelatinized grains are more swollen, have thin 

 instead of thick capsules, and are not so much distorted 

 as in N, albicans. 



The reaction with chromic acid begins in 30 seconds. 

 Complete gelatiuization occurs in less than 0.5 per cent 

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

 total starch in 5 minutes; in about 3 per cent of the 

 grains and 75 per cent of the total starch in 15 minutes; 

 in about 57 per cent of the grains and 98 per cent of the 

 total starch in 30 minutes; in about 95 per cent of the 

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

 and in more than 99 per cent of the same in 60 minutes. 

 (Chart D 312.) (See footnote, page 516.) 



The hilum becomes distinct, and the lamella; are dis- 

 tinct in all of the grains. Gelatinization begins at the 

 hilum and progresses according to two methods. In 

 a small majority of the grains the portion immediately 

 surrounding the hilum, which in some grains represents 

 a primary starch formation, but which in others can not 

 be definitely distinguished as such, is divided and sub- 

 divided by fissures into a number of rather coarse, 

 distinct granules. Then a sheaf of irregular fissures 

 extends from the hilum toward both the proximal and 

 the distal margin or only toward the distal margin, 

 dividing the material in their path into granules; the 

 rest of the substance of the grain is rather finely striated. 

 The gramilar material around the hilum begins to 

 gelatinize first, although portions of it are very resistant 

 and remain uugelatinized until the grain is finally dis- 

 solved, and then the portion traversed by the sheaf of 

 fissures. The striated portion of the grain is pushed 

 to the margin on either side as the grain swells, where 

 it forms a finely striated band. This becomes thinner 

 and more refractive, and the striae become coarse as gela- 

 tinization progresses; finally the capsule is dissolved at 

 one of the points reached by the fissures from the hilum, 

 and the contents of the grain flow out and are dissolved. 

 In the second type ; which is soon in a largo minority of 



the grains, two furrows or fissures proceed transversely 

 or obliquely from the hilum to the margin, and the 

 material included between the hilum and the distal 

 margin is divided by coarse stria; into rows of coarse 

 granules arranged as are the lamella; in the untreated 

 grain. A narrow baud of starch which is not so nar- 

 row at the proximal end is not so divided, but is finely 

 striated. The grain begins to gelatinize from the hilum 

 outward and before gelatinization is complete the cap- 

 sules and the marginal band of starch at the distal 

 margin are dissolved and the contents of the grain flow 

 out of this opening and also are dissolved. The grains 

 are always dissolved before gelatiuization is complete. 



Comparison of the chromic-acid reactions between 

 N. absci-ssus and N. albicans shows: 



The hilum and lamella; are as distinct as in JV. 

 albicans, but the lamellar structure remains visible dur- 

 ing a greater part of the reaction than in that starch. 

 Gelatiuization progresses according to two methods, and 

 that observed in the great majority of the grains bears 

 very little resemblance to that seen in a small majority 

 of the grains of N. albicans. The starch immediately 

 around the hilum or the primary starch is divided by 

 many fissures into particles which are divided and sub- 

 divided until the central portion of the interior of the 

 grain is filled with a mass of fine granules. The starch 

 surrounding this portion, which is probably a secondary 

 formation, is coarsely striated, and as the primary 

 starch and the less resistant part of the secondary starch 

 are gelatinized and the grain swells the more resistant 

 part of the secondary starch forms a coarsely striated 

 marginal band which is thinner in some places than in 

 others. This baud gradually grows thinner and more 

 nearly transparent, and is eventually dissolved at the 

 points where it is thin. In some grains the primary 

 starch only forms large particles which are very resistant 

 and remain after the rest of the grain is dissolved. The 

 second method, which is seen in only a small number of 

 grains, is very like that noted in a large minority of the 

 grains of N. albicans, and the main differences noted 

 are that just distal to the primary furrows or fissures 

 are two sheaves of fine irregular fissures, and the ma- 

 terial divided by these fissures is the first to gelatinize. 

 The remainder of the distal starch is not striated, but 

 loses its original structural appearance and becomes a 

 finely granular mass. There is a narrow band of mate- 

 rial around the entire margin, as in N. albicans, but is 

 coarsely striated, especially at the proximal end. It is 

 dissolved at the distal end of the grains after the starch 

 in the interior is nearly gelatinized and the contents 

 of the grain flow out and are dissolved. The proximal 

 portion is the last to be gelatinized. The grains, as in 

 N. albicans, are always dissolved before gelatinization is 

 complete. 



The reaction with pyroyallif acid begins in 30 sec- 

 onds. Complete gelatiuization occurs in about 3 per 

 cent of the entire number of grains and 25 per cent of 

 the total starch in 5 minutes; in about 31 per cent of 

 the grains and 78 per cent of the total starch in 15 min- 

 utes ; in about 69 per cent of the grains and 91 per cent 

 of the total starch in 30 minutes ; in about 75 per cent 

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

 45 minutes; and in about 85 per cent of the grains and 



