730 



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



77 per cent of the grains and 90 per cent of the total 

 starch in 15 minutes; in about 97 per cent of the grains 

 and in more than 99 per cent of the total starch in 30 

 minutes. ( Chart D 554.) 



The hilum and the lamellae are more distinct than in 

 M. arnoldiana. Gelatinization begins at the hilum and 

 progresses according to the two methods seen in M. 

 arnoldiana. The method noted in the elongated grains, 

 which are in the majority in this starch, varies somewhat 

 from that found in the elongated grains of M. arnoldiana. 

 The method in this starch is as follows : 2 fissures or fur- 

 rows are seen to extend obliquely from the hilum on either 

 side, half the distance from the hilum to the distal mar- 

 gin. The starch between these 2 fissures is separated into 

 filaments or bundles of filaments by a double row of 

 fissures which slant proximally from the 2 original 

 furrows or fissures to the longitudinal axis of the grain. 

 The starch just proximal to the hilum and on the sides is 

 divided into a number of coarse granules by regular 

 radiating cracks or fissures. The rest of the starch at 

 the proximal end and sides forms a thick homogeneous, 

 refractive-looking marginal band and that at the distal 

 end forms a broad refractive, rather thin band. The 

 grain swells and the starch which is divided into fila- 

 ments is partially gelatinized, leaving a granular residue. 

 These granules in conjunction with those proximal to the 

 hilum form a granular ring within the homogeneous 

 ring just described. The outer homogeneous ring grows 

 broader and more nearly transparent and is finally dis- 

 solved, usually at the distal end first, but in some grains 

 at the side first. The granular ring, although it grows 

 more and more hyaline, is dissolved later, and it also 

 dissolves first at the distal end. In the second method, 

 which is seen in a minority of the grains which are also 

 those of broad forms, there are no differences noted be- 

 tween this starch and that of M. arnoldiana. 



The reaction with pyrogallic acid begins in 1 minute. 

 Complete gelatinization occurs in about 2 per cent of the 

 entire number of grains and 11 per cent of the total 

 starch in 5 minutes; in about 11 per cent of the grains 

 and 54 per cent of the total starch in 15 minutes; in 

 about 42 per cent of the grains and 73 per cent of the 

 total starch in 30 minutes; in about 61 per cent of the 

 grains and 81 per cent of the total starch in 45 minutes ; 

 in about 63 per cent of the grains and 84 per cent of the 

 total starch in 60 minutes. (Chart D 555.) 



The hilum and the lamella? both become more distinct 

 than in M. arnoldiana. Gelatinization begins at the 

 hilum and progresses according to two methods which 

 are very similar to those described under M. arnoldiana. 

 The method which is seen in the majority of the grains 

 is similar to that noted in a minority of the grains of 

 M. arnoldiana. The hilum swells slightly and 2 fissures 

 extend obliquely on either side toward the distal margin, 

 but do not penetrate 'as near it as in M . arnoldiana. The 

 starch comprehended between these fissures is divided 

 immediately into filaments or bundles of filaments by 2 

 rows of fissures which slant proximally from the 2 origi- 

 nal furrows or fissures toward the longitudinal axis of the 

 grain. Only a small part of the starch distal to the 

 hilum is gelatinized in this way, which is a variation 

 from that of M. arnoldiana in which the greater part of 

 the distal starch was so gelatinized; the rest of the 

 starch to the distal margin becomes increasingly hya- 



line and shrinks in a way that suggests that the less re- 

 sistant starch was being gelatinized. Finally it forms 

 a broad, very granular and irregular mass at the distal 

 margin which is later gelatinized with much distortion 

 of the capsule. The starch proximal to the hilum and 

 outside the 2 original oblique furrows or fissures forms 

 a homogeneous-looking, refractive band, with the excep- 

 tion of that portion which immediately surrounds the 

 hilum. This is divided into coarse granules by short 

 fissures at regular intervals. No such phenomenon is 

 seen in M. arnoldiana. As the marginal band gradually 

 becomes thinner and more hyaline in appearance, these 

 granules grow thinner and more hyaline also, but are 

 often the last part of the grain to be gelatinized. The 

 second method which is seen in a minority of the grains 

 is very nearly the same as that which has been described 

 for a majority of the grains of M. arnoldiana. The only 

 differences noted are that the starch distal to the 2 

 longitudinal fissures and the hilum becomes more nearly 

 homogeneous in appearance and is not divided into pyra- 

 midal masses by wedge-shaped fissures, but merely grows 

 gradually less in amount, and finally forms a broader 

 and somewhat more irregularly granular mass at the 

 distal margin. The gelatinized grains are as much swol- 

 len, have thicker capsules, and are even more distorted, 

 especially at the distal end, than in M. arnoldiana. 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in about 52 per cent of 

 the entire number of grains and 67 per cent of the total 

 starch in 15 seconds; in about 68 per cent of the grains 

 and 80 per cent of the total starch in 30 seconds ; in about 

 73 per cent of the grains and 90 per cent of the total 

 starch in 5 minutes; in about 80 per cent of the grains 

 and 93 per cent of the total starch in 15 minutes; in about 

 the same percentage of the grains and 96 per cent of the 

 total starch in 30 minutes. (Chart D 556.) 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 70 per cent of 

 the entire number of grains and 75 per cent of the total 

 starch in 30 seconds ; in about 90 per cent of the grains 

 and 93 per cent of the total starch in 45 seconds ; in 95 

 per cent of the grains and 96 per cent of the total starch 

 in 1 minute. (Chart D 557.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in more than 58 

 per cent of the entire number of grains and 85 per cent 

 of the total starch in 30 seconds; in about 77 per cent 

 of the grains and 93 per cent of the total starch in 1 

 minute ; in about 88 per cent of the grains and 98 per cent 

 of the total starch in 3 minutes; in about 91 per cent of 

 the grains and 99 per cent of the total starch in 5 min- 

 utes. ( Chart D 558.) 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 73 per 

 cent of the entire number of grains and 81 per cent of 

 the total starch in 15 seconds; in about 81 per cent of 

 the grains and 93 per cent of the total starch in 30 

 seconds; in about 84 per cent of the grains and 95 per 

 cent of the total starch in 1 minute. (Chart D 559.) 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 50 per 

 cent of the entire number of grains and 75 per cent of 

 the total starch in 1 minute ; in about 60 per cent of the 

 grains and 85 per cent of the total starch in 3 minutes ; 



