676 



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



Temperature Reactions. 

 The majority of the grains are gelatinized at 83° to 

 84.5° C, and of all at 84° to 86° C, mean 85° C, dis- 

 tinctly higher than in G. tristis. 



Effects of Various Reagents. 



The reaction with chloral hydrate begins imme- 

 diately. Complete gelatinization occurs in about 14 per 

 cent of the grains and 22 per cent of the total starch 

 in 5 minutes; in about 36 per cent of the grains and 

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

 48 per cent of the grains and 51 per cent of the total 

 starch in 30 minutes ; in about 49 per cent of the grains 

 and 52 per cent of the total starch in 45 minutes ; in about 

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

 starch in 60 minutes. (Chart D 463.) 



The hilum becomes very prominent and there is 

 usually a small bubble formed. From the hilum to the 

 distal corners of the grain are two lines or canals which 

 appear to divide the material of the grain into two por- 

 tions. The lamella;, which are not distinct at first, later 

 become moderately distinct and may be seen to be trans- 

 versed by fine radiating lines. A refractive band is slowly 

 formed and surrounds a part of the margin of the grain. 

 It is narrow and appears to be confined to the margin. 

 Gelatinization begins at the distal margin, usually at 

 the corners of the pressure facets. The simple grains 

 are most quickly and most frequently affected, many of 

 the compound grains and of the aggregates not being 

 gelatinized at all; in those which are gelatinized, how- 

 ever, gelatinization begins at the distal margin of the 

 components as in the case of the simple grains. After 

 this preliminary gelatinization, the fine radiating lines 

 before noted become larger and divide the lamella; into 

 rows of granules, the hilum swells, and the granules are 

 pushed to the margin and then gelatinized, and as the 

 starch between the hilum and the distal margin is the 

 most resistant part of the grain it is gelatinized last. 

 The gelatinized grains are large and somewhat distinct, 

 but still retain some of the original form of the grain. 



The reaction with chromic acid begins in a few grains 

 in 1 minute. Complete gelatinization occurs in about 1 

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

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

 the grains and 20 per cent of the total starch in 15 min- 

 utes; in about 25 per cent of the grains and 75 per cent 

 of the total starch in 30 minutes ; in about 28 per cent 

 of the grains and 90 per cent of the total starch in 45 

 minutes; in about 53 per cent of the grains and 96 per 

 cent of the total starch in 60 minutes. (Chart D 464.) 



The reaction with pyrogallic acid begins in a few 

 grains in half a minute. Complete gelatinization occurs 

 in about 5 per cent of the entire number of grains and 

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

 li per cent of the grains and 10 per cent of the total starch 

 in 15 minutes; very slight advance in 30 minutes; in 

 about 8 per cent of the grains and 12 per cent of the 

 total starch in 45 minutes; about the same in 60 minutes. 

 (Chart D465.) 



The reaction with nitric acid begins in a few grains 

 immediately. Complete gelatinization occurs in about 2 

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

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

 of the grains and 4 per cent of the total starch in 15 



minutes; in about 4 per cent of the grains and 6 per 

 cent of the total starch in 30 minutes; in about 4 per 

 cent of the grains and 8 per cent of the total starch in 

 45 minutes; in about the same percentage of both the 

 grains and total starch in 60 minutes. (Chart D 466.) 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 44 per cent of 

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

 starch in 5 minutes ; in about 70 per cent of the grains 

 and 97 per cent of the total starch in 15 minutes;, in 

 about 86 per cent of the grains and over 99 per cent of 

 the total starch in 30 minutes ; in about 99 per cent of 

 the grains and over 99 per cent of the total starch in 45 

 minutes. (Chart D 467.) 



The reaction with hydrochloric acid begins imme- 

 diately. Complete gelatinization occurs in about 5 per 

 cent of the entire number of grains and 12 per cent of 

 the total starch in 5 minutes ; in about 7 per cent of the 

 grains and 22 per cent of the total starch in 15 min- 

 utes; in about 12 per cent of the grains and 32 per 

 cent of the total starch in 30 minutes; in about 15 

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

 starch in 45 minutes; in about 20 per cent of the 

 grains and 68 per cent of the total starch in 60 minutes. 

 (Chart D 468.) 



Gelatinization in many grains begins simultaneously 

 at the margin and in the mesial region. When the mar- 

 gin is affected the capsule becomes much distended and 

 thrown into folds, and after the process has progressed 

 inward through a narrow border this delicate folded area 

 appears to dissolve. The process of gelatinization is now 

 more rapid along the courses of fissures which proceed 

 from the hilum, causing the mesial region to be disor- 

 ganized into very refractive granules surrounded by a 

 few lamella; which are profusely striated. At the end 

 of the experiment (60 minutes) the grains are much 

 swollen, but only a comparatively small percentage are 

 completely gelatinized, the majority having the mesial 

 region bounded by a border of ungelatinized lamella;. 

 The smaller and medium-sized grains are to a larger 

 extent gelatinized, and sometimes become disintegrated 

 and rarely dissolved. 



The reaction with potassium hydroxide begins im- 

 mediately. Complete gelatinization occurs in about 5 

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

 of the total starch in 5 minutes; in about 7 per cent of 

 the grains and 14 per cent of the total starch in 15 

 minutes ; in about 12 per cent of the grains and 22 per 

 cent of the total starch in 30 minutes; in about 20 per 

 cent of the grains and 28 per cent of the total starch in 

 45 minutes; in about 24 per cent of the grains and 32 

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

 D469.) 



The reaction with potassium iodide begins imme- 

 diately. Complete gelatinization occurs in about 5 per 

 cent of the entire number of grains and 7 per cent of 

 the total starch in 5 minutes ; in about 6 per cent of the 

 grains and 12 per cent of the total starch in 15 min- 

 utes; in about 9 per cent of the grains and 15 per 

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

 same percentage of the grains but about 19 per cent 

 of the total starch in 45 minutes; in about 12 per 

 cent of the grains and 22 per cent of the total starch in 

 60 minutes. (Chart D 470.) 



