638 



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



The results obtained with this reagent are very con- 

 flicting unless studied in clear weather as the solution 

 tends to darken the field so that the final stages are 

 difficult to ascertain. 



The reaction with pyrogallic acid begins in 30 sec- 

 onds. Complete gelatinization occurs in less than 0.5 

 per cent of the entire number of grains and 22 per cent 

 of the total starch in 5 minutes; in about 30 per cent 

 of the grains and 72 per cent of the total starch in 

 15 minutes; in about 43 per cent of the grains and 81 

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

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

 starch in 45 minutes ; in about 54 per cent of the grains 

 and 90 per cent of the total starch in 60 minutes. (Chart 

 D381.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in about 24 per cent of 

 the entire number of grains and 58 per cent of the total 

 starch in 5 minutes; in about 33 per cent of the grains 

 and 73 per cent of the total starch in 15 minutes ; in about 

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

 starch in 30 minutes ; in about the same percentage of the 

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

 in about 44 per cent of the grains and 84 per cent of the 

 total starch in 60 minutes. (Chart D 382.) 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 62 per cent of 

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

 starch in 2 minutes ; in about 89 per cent of the grains 

 and 99 per cent of the total starch in 5 minutes. (Chart 

 D 383.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 15 per 

 cent of the entire number of grains and 53 per cent of 

 the total starch in 5 minutes; in about 36 per cent of the 

 grains and 63 per cent of the total starch in 15 minutes ; 

 in about 45 per cent of the grains and 72 per cent of the 

 total starch in 30 minutes; in about 50 per cent of the 

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

 in about 59 per cent of the grains and 86 per cent of 

 the total starch in 60 minutes. (Chart D 384.) 



The hilum becomes very distinct, unattended by the 

 formation of a bubble. The lamellae also are distinct, but 

 later become obscured. Gelatinization begins at the 

 hilum and is preceded by an extension and widening of 

 2 refractive lines or fissures which, in the untreated 

 grain, extend distally in the interior of the grain from 

 either side of the hilum. The starch included between 

 these fissures and the hilum and the distal margin be- 

 comes more refractive in appearance and is divided into 

 fine granules which are arranged in rows corresponding 

 to the line of the lamellae. In most grains the starch 

 near the hilum is divided first into irregularly shaped 

 granules which are very resistant. Gelatinization now 

 begins with swelling of the hilum, and the finely granu- 

 lar portion, but not the coarse granules immediately sur- 

 rounding the hilum, begins to gelatinize. Before gela- 

 tinization reaches the distal end, the granular starch 

 here is invaded by several longitudinal fissures from the 

 margin, which divide the material and apparently hasten 

 gelatinization. The more resistant portion in the proxi- 

 mal end and sides, in the meantime, forms a thick, 

 indistinctly striated and lamellated marginal band 

 around the inner border, of which the rather coarse 



granules formed from the starch around the hilum 

 are arranged at nearly regular intervals. This band be- 

 comes progressively thinner and more nearly transparent 

 and finally is also gelatinized, the proximal margin last, 

 and some time after the distal material is gelatinized, 

 only the thin capsule and the resistant granules already 

 mentioned are left. These granules persist for some 

 time, growing smaller and more refractive and are finally 

 gelatinized, llarely the most resistant granules are 

 found grouped together at the distal margin, and in such 

 grains the proximal end and the marginal portion at 

 the sides is gelatinized before the starch between the 

 hilum and the distal end. 



The gelatinized grains are large, thin-walled, not 

 much distorted, except at the distal end, and retain 

 some resemblance to the form of the untreated grain. In 

 a moderate number of grains, dissolution of the capsule 

 at various points and invasion of the grain by cracks at 

 these points take place long before gelatinization is com- 

 plete, and such grains become coarsely granular through- 

 out, and are gelatinized and nearly completely dissolved 

 so that only the curled-up capsule remains. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization occurs in about 38 per 

 cent of the entire number of grains and 82 per cent of 

 the total starch in 5 minutes ; in about 44 per cent of the 

 grains and 86 per cent of the total starch in 15 minutes ; 

 in about 55 per cent of the grains and 89 per cent of the 

 total starch in 30 minutes; in about 58 per cent of the 

 grains and 93 per cent of the total starch in 45 minutes; 

 in about 65 per cent of the grains and 95 per cent of the 

 total starch in 60 minutes. (Chart D 385.) 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 24 per 

 cent of the grains and 52 per cent of the total starch in 

 5 minutes; in about 29 per cent of the grains and 68 

 per cent of the total starch in 15 minutes; in about 32 

 per cent of the grains and 78 per cent of the total starch 

 in 30 minutes; in about 39 per cent of the grains and 

 86 per cent of the total starch in 45 minutes ; in about 

 43 per cent of the grains and 89 per cent of the total 

 starch in 60 minutes. (Chart D 386.) 



The hilum is distinct and if 2 refractive fissures 

 already exist in the untreated grain, they become wider 

 and more extensive, and if not already present they 

 quickly form. The lamellae are at first moderately dis- 

 tinct, and become more distinct, then less distinct, and 

 are finally obliterated. Gelatinizafcion begins at the 

 hilum which swells slightly, and in the portion of the 

 grain included between the 2 fissures, already described, 

 the hilum, and the distal margin becomes more re- 

 fractive, and is divided into irregularly placed gran- 

 ules. In the majority of the grains, this granular mass 

 is invaded at the distal margin by longitudinal fissures', 

 and is the first part of the grain to be gelatinized. 

 This is followed at once by the part immediately distal 

 to the hilum, leaving the portion midway between the 

 hilum and the distal margin ungelatinized, and this may 

 remain so for a considerable time. The most resistant 

 portion of the grain, however, is at the proximal end 

 and sides nearby. As the hilum and the grain enlarge, 

 this material forms a faintly lamellated, non-striated, 

 marginal band which slowly becomes thinner and more 

 nearly transparent until only the capsule is left. In a 



