742 



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



to 68° C, mean 67.5° C. The outermost marginal 

 lamella? at the proximal end and sides nearby are less 

 resistant than in P. grandifolius. 



Effects of Various Reagents. 



The reaction with chloral hydrate begins in a few 

 grains immediately. Complete gelatinization occurs in 

 about 14 per cent of the entire number of grains and 27 

 per cent of the total starch in 5 minutes; in about 48 

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

 in 15 minutes; in about 55 per cent of the grains and Gl 

 per cent of the total starch in 30 minutes; in about G2 per 

 cent of the grains and 67 per cent of the total starch in 

 45 minutes; little if any further change in GO minutes. 

 (Chart D 574.) 



The hilum becomes more distinct than in P. grandi- 

 folius and a bubble is formed there, more frequently 

 than in P. grandifolius; and two lines, and also more 

 frequently two folds or wrinkles, in the capsule are seen 

 extending from the hilum to the distal margin, as in 

 P. grandifolius. The lamelhe become more distinct than 

 in P. grandifolius, and a refractive band, broad at the 

 proximal end, and in which the lamella? are more distinct, 

 is quickly formed about the margins of the grains. Gela- 

 tinization (unlike in the grains of P. grandifolius) be- 

 gins at the proximal end in most of the grains, accom- 

 panied by rapid swelling of the hilum, and then at the 

 distal end; in some others at the sharp corners at the 

 distal end and then at the proximal end ; and in a few it 

 proceeds entirely from the distal end, the proximal end 

 being the most resistant. The progress of gelatinization 

 is essentially the same as in P. grandifolius, and the cup- 

 shaped hollows noted in the more resistant grains of that 

 starch are here not quite so numerous or so deep. The 

 gelatinized grains are very large and more distorted than 

 in P. grandifolius and retain less of the form of the 

 untreated grain. 



The reaction with chromic acid begins immediately. 

 Complete gelatinization occurs in about 10 per cent of the 

 entire number of grains and 67 per cent of the total 

 starch in 5 minutes; in about 61 per cent of the grains 

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

 99 per cent of both the grains and total starch in 30 

 minutes. (Chart D 575.) 



The hilum is more distinct than in P. grandifolius, 

 and no bubble is observed to form there. The lamella; 

 are at first more distinct than in P. grandifolius, but 

 later are obscured and do not reappear as in P. grandi- 

 folius. A refractive band (broader at the proximal 

 end and not visible at the distal end) is observed to form 

 about the margins of some of the grains. Gelatiniza- 

 tion, as in P. grandifolius, begins at the hilum. Two 

 lines of fissures extend distally from the hilum just inside 

 the line made by the refractive band noted above, and 

 these branch out extensively in all directions through the 

 grain, dividing the starch into many coarse granules. 

 The starch immediately proximal to the hilum, in the 

 meantime, is rapidly gelatinized, forming a broad canal 

 from the hilum to the thin capsule. Then as the granular 

 starch becomes gelatinous, the capsule at the proximal 

 end or at one of the distal corners is dissolved, and the 

 gelatinous starch flows out and is dissolved. The dis- 

 solution of the capsule is much later in the process of 

 gelatinization than in P. grandifolius and the grains 



collapse and are dissolved more rapidly after it has 

 taken place than in those grains. Shreds of the capsule 

 remain and dissolve more slowly than the rest of the 

 grain as in P. grandifolius. 



The reaction with pyrogallic acid begins immediately. 

 Complete gelatinization occurs in about 16 per cent of the 

 entire number of grains and 63 per cent of the total 

 starch in 5 minutes ; in about 43 per cent of the grains 

 and 80 per cent of the total starch in 15 minutes; in 

 about 57 per cent of the grains and 85 per cent of the 

 total starch in 30 minutes; in about 68 per cent of the 

 grains and 91 per cent of the total starch in 45 minutes; 

 in about 71 per cent of the grains and 94 per cent of the 

 total starch in 60 minutes. (Chart D 576.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in about 55 per cent of the 

 entire number of grains and 90 per cent of the total 

 starch in 1 minute ; in about 93 per cent of the grains and 

 99 per cent of the total starch in 5 minutes; in about 96 

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

 starch in 10 minutes; in over 99 per cent of both the 

 grains and total starch in 15 minutes. (Chart D 577.) 



The hilum swells and a bubble frequently appears 

 which enlarges even less and is as a rule more transient 

 than in P. grandifolius. Gelatinization with extension 

 is more marked at the proximal end, and the central 

 portion of the distal end is more resistant than in P. 

 grandifolius. The most resistant grains are those similar 

 in shape and with the narrow refractive resistant border 

 at proximal end and sides, as in P. grandifolius. The 

 gelatinized grains are swollen and more distorted, espe- 

 cially at the proximal end, than in P. grandifolius. 



The reaction with sulphuric acid begins immediately. 

 Complete gelatinization occurs in about 88 per cent of the 

 entire number of grains and 96 per cent of the total 

 starch in 1 minute; in over 99 per cent of both the 

 grains and total starch in 2 minutes; complete gela- 

 tinization (100 per cent) in 2 minutes and 30 seconds. 

 (Chart D578.) 



The reaction with hydrochloric acid occurs imme- 

 diately. Complete gelatinization occurs in about 95 per 

 cent of the entire number of grains and over 99 per cent 

 of the total starch in 1 minute; all but parts of rare 

 grains, over 99 per cent of both the entire number of 

 grains and total starch in 1 minute and 30 seconds. 

 (Chart D579.) 



The hilum, as in P. grandifolius, becomes very dis- 

 tinct, but no bubble is formed there. The lamellae are 

 more distinct than in P. grandifolius. A very refrac- 

 tive band is formed, as in P. grandifolius, about the 

 margin of the grain before gelatinization begins, and 

 this is broader at the proximal than at the distal end. 

 Gelatinization begins at the hilum, as in P. grandifolius, 

 but no granules are formed immediately about the hilum 

 as in those grains. Two lines of fissures extend distally 

 from the hilum and these by many irregular branches 

 divide the starch of the grain into coarse granules which 

 do not show much of a lamellar arrangement and in 

 this respect differ from those found in the grains of 

 P. grandifolius. Otherwise the process is the same as 

 noted under P. grandifolius. The gelatinized grains are 

 large, very nearly transparent, very thin-walled, and more 

 distorted at the distal end than in P. grandifolius. 



