764 



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



TEMPERATUBE REACTIONS. 



The temperature of gelatinization of the majority 

 of the grains is 58 to 59.5 C., and of all but rare re- 

 sistant grains is 65 to 66.5 C., mean 65.75 C. The 

 most resistant grains are the very small and the rare 

 scattered quite large isolated grains of the disaggregate 

 type. A larger number of both are present than in 

 ( '. lowianum. 



EFFECTS OF VARIOUS REAGENTS. 



The reaction with chloral hydrate begins immedi- 

 ately. Complete gelatinization occurs in about 90 per 

 cent of the entire number of grains and 92 per cent of the 

 total starch in 2 minutes ; in about 95 per cent of the 

 grains and 97 per cent of the total starch in 3 minutes; 

 in over 99 per cent of the grains and total starch in 5 

 minutes. (Chart D 616.) 



The hilum becomes very distinct, and a bubble is 

 rarely formed there. The lamellae become distinct in the 

 more resistant grains, but just before they are gelatinized 

 they become indistinct as the starch composing them be- 

 comes finely granular. A refractive band is formed about 

 the margin of the more resistant grains and recedes 

 inward as gelatinization progresses. Gelatinization be- 

 gins always at the distal margin, and occasionally this is 

 followed immediately by gelatinization of the proximal 

 margin. Gelatinization progresses from these initial 

 points as in C. lowianum, the most resistant starch, how- 

 ever, being always just distal to the hilum and never in 

 a central core. The gelatinized grains are moderately 

 large and not much distorted, and retain more of the 

 forms of the untreated grains than do those of C. 

 lowianum. 



The reaction with chromic acid begins immediately. 

 Complete gelatinization occurs in about 77 per cent of 

 the entire number of grains and 97 per cent of the total 

 starch in 2 minutes ; in about 96 per cent of the grains 

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



The hilum is not so distinct as in C. lowianum and 

 the lamellae are usually not visible. Gelatinization as in 

 C. lowianum begins at the hilum and is the same as in 

 those grains except that no granules are formed of the 

 starch near the hilum and the grain is at no time ob- 

 served to be covered by fine strias. Dissolution of the 

 capsule takes place somewhat more rapidly than in C. 

 lowianum. 



The reaction with pyrogallic acid begins immediately. 

 Complete gelatinization occurs in about 69 per cent of 

 the grains and 95 per cent of the total starch in 5 min- 

 utes ; in about 94 per cent of the grains and 99 per cent 

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

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

 30 minutes; little if any further advance in 45 and 60 

 minutes, respectively. (Chart D 617.) 



The reaction with nitric acid begins immediately; 

 nearly all the grains are gelatinizd in 15 seconds ; all but 

 rare resistant ones in 45 seconds; these may resist the 

 reaction for from 3 to 6 minutes. 



The margin is the most resistant part of the grains, 

 especially the margin in the separated components of 

 aggregates which are much more numerous than in C. 

 lowianum. The reaction is qualitatively about the same 

 as in C. lowianum, the process is so rapid that no minute 

 differences in detail can be detected, with the exception 



that imagination does not usually accompany the reac- 

 tion. The gelatinized grains are swollen but not usually 

 distorted, much less than in C. lowianum. The wall 

 of the gelatinized grain is thicker than in C. lowianum. 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in all but rare grains, and 

 over 99 per cent of both grains and total starch in 15 

 seconds; in all grains (100 per cent) in 25 seconds. 



The reaction with hydrochloric acid begins imme- 

 diately, all but a few grains are completely gelatinized 

 in 10 seconds, all in 15 seconds. The reaction is so 

 rapid that the minute steps can not be studied as in 

 C. lowianum. 



The gelatinized grains are swollen but many are 

 not distorted and others show but slight distortion, less 

 distortion than in C. lowianum. The capsule is thicker 

 and more refractive as well as much more resistant than 

 in C. loirianum since it remains undissolved in many 

 grains in 45 minutes, but in 60 minutes the capsule of all 

 but rare grains passes into solution. 



The reaction with potassium hydroxide begins imme- 

 diately. Complete gelatinization of all grains occurs in 

 10 seconds and probably sooner since the reaction is 

 completed by the time the coverslip is adjusted and the 

 slide under observation. The details of the reaction can 

 not be satisfactorily stated as noted in C. lowianum. 



The gelatinized grains are much swollen as in C. 

 lowianum, but distortion is much less frequent and the 

 capsule is considerably thicker. 



The reaction with potassium iodide begins imme- 

 diately; nearly all are gelatinized in 15 seconds; all but 

 rare resistant grains in 30 seconds, these usually in 45 

 seconds, rarely in 1 minute. The reaction is too rapid, 

 as in C. lowianum, to make detailed observations. The 

 gelatinized grains are swollen, but very little distorted, 

 much less than in C. lowianum; they, unlike this species, 

 do resemble the shape of the untreated grain. The cap- 

 sule is thicker than in C. lowianum. 



The reaction with potassium sulphocyanatc begins 

 immediately; nearly all the grains are gelatinized in 5 

 seconds, all in 10 seconds. The reaction is qualitatively 

 about the same as in C. lowianum, but the process is 

 so rapid that the details can not be satisfactorily 

 determined. 



The gelatinized grains are much swollen, but only 

 slightly distorted ; the distortion is less and the wall of 

 the grain thicker than in C. lowianum. The gelatinized 

 grains usually resemble the form of the untreated grain, 

 more than in C. loivianum. 



The reaction with potassium sulphide is instan- 

 taneous ; no details can be determined as in C. lowianum. 

 The gelatinized grains are much swollen and distorted, 

 though somewhat less distorted than in 0. lowianum. 



The reaction with sodium hydroxide begins imme- 

 diately ; all the grains are gelatinized but a few resistant 

 in 10 seconds; all in 15 seconds. The reaction is so 

 rapid, that the minute steps can not be studied, as is 

 the case with C. lowianum. 



The gelatinized grains are much swollen, and usually 

 but slightly distorted ; they are less distorted and have a 

 thicker wall than in C. lowianum. The gelatinized 

 grains usually bear some resemblance to the form of 

 the untreated grains, much closer than C. lowianum. 



