628 



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



bottle-shaped, almost round, irregularly quadrilateral 

 with rounded angles, and clam-shell-shaped. The broader 

 forms are somewhat flattened and when seen on edge 

 have an elongated ovoid or elliptical shape. 



The hilum when it is not fissured is a moderately 

 distinct, round, or lenticular-shaped spot. It is fissured 

 in a majority of the grains and the fissures have the fol- 

 lowing forms: (1) A small straight or curved horizontal 

 or oblique line which is often somewhat branched; (2) 

 a Yor T figure; (3) an irregularly stellate arrangement 

 of fissures. The hilum is eccentric from 0.4 to 0.09, 

 usually 0.16, of the longitudinal axis. 



The lamella; are moderately distinct and fine. Near 

 the hilum they are fine and have the form of a regular, 

 continuous, round, or oval ring. In the rest of the grain 

 they are discontinuous near the distal end and have, 

 in general, the form of the outline of the grain, but are 

 often wavy in outline. There is usually 1 broad refrac- 

 tive lamella situated about two-thirds to three-fourths 

 of the distance from the hilum to the distal margin, which 

 is continuous and which separates the finer proximal 

 lamella; from those at the distal end which are not so 

 fine. The number of lamella; counted on the larger 

 grains varies from 24 to 40, commonly 34. 



In size the grains vary from the smaller which are 

 6 by 5/t, to the larger broad forms which are 68 by 60/x, 

 rarely 70 by 90/*, to the larger elongated grains which 

 are 66 by 36/x, in length and breadth. The common t sizes 

 are 44 by 44/* and 44 by 30/*. 



Polariscopic Properties. 



The figure is distinct, but usually not well defined. 

 The lines are rather thick and tend to be diffused near the 

 margin. They sometimes cross at a right angle, but 

 usually at an acute angle whose size varies somewhat in 

 the different grains. They are usually bent, sometimes 

 very greatly, but are rarely bisected. In some of the 

 figures there is a cross-bar which connects the long arms of 

 the cross about one-half to two-thirds of the distance 

 from the hilum to the margin. 



The degree of polarization varies from low to high 

 (value 55). In most of the grains it is medium, but in 

 a few low, and in a few high. There is considerable 

 variation in a given aspect of an individual grain. 



With selenite the quadrants are usually not clear-cut. 

 They are very unequal in size and irregular in shape. 

 The colors are usually pure. They have a greenish tinge 

 in rare grains. 



Iodine Reactions. 



With 0.25 per cent Lugol's solution the grains all 

 color a light to moderate blue-violet (value 40), and the 

 color deepens with moderate rapidity until it is deep 

 and more bluish. With 0.125 per cent Lugol's solution 

 the grains all color a light blue-violet, and the color 

 deepens with moderate rapidity until moderately deep. 

 After heating in water until all the grains are completely 

 gelatinized and then treating with a 2 per cent Lugol's 

 solution, the gelatinized grains all color a deep to a 

 moderate indigo, and the solution ia moderately deep 

 indigo. If the preparation is boiled for 2 minutes and 

 then treated with an excess of a 2 per cent Lugol's solu- 

 tion, the grain residues color a light to moderate indigo- 

 blue, all the capsules a very deep violet, and the solution 

 a very deep indigo. 



Aniline Reactions. 



With gentian violet the grains all color, very lightly, 

 at once, and in 30 minutes they are moderate to deeply 

 colored (value 65). In most of the grains the distal end 

 is more deeply colored than the rest of the grain. 



With safranin the grains all color very lightly at 

 once, and in 30 minutes they are moderate to deeply 

 colored (value 65). In most of the grains the distal 

 end is more deeply colored than the rest of the grain. 



Temperature Reactions. 

 The temperature of gelatinization of the majority 

 of the grains is 58° to 60.5° C, and of all is 61° to 

 63° C; the mean is 62° C. 



Effects of Various Reagents. 



The reaction with chloral hydrate begins in 30 sec- 

 onds. Complete gelatinization occurs in about 14 per 

 cent of the entire number of grains and 57 per cent of the 

 total starch in 5 minutes; in about 59 per cent of the 

 grains and 84 per cent of the total starch in 15 minutes; 

 and in about 86 per cent of the grains and 95 per cent 

 of the total starch in 30 minutes. (Chart D 373.) 



The hilum becomes distinct, attended by the forma- 

 tion of a bubble in rare grains. The lamella? are never 

 visible. The grain becomes more refractive, the first' 

 portion to show cleavage being a very narrow strip at 

 the margin. Gelatinization begins at the proximal end, 

 followed quickly by the gelatinization of the margin of 

 one side and of the distal end. From here it spreads 

 around the whole margin, only a very narrow strip being 

 gelatinized. Gelatinization progresses inwards, preceded 

 by short fissures which break off particles which are then 

 gelatinized. The last part of the grain to be gelatinized 

 is that just distal to the hilum. The gelatinized grains 

 are much swollen, have thin capsules, and are very 

 much distorted. 



The reaction with chromic acid begins immediately. 

 Complete gelatinization occurs in about 55 per cent of 

 the entire number of grains and 91 per cent of the total 

 starch in 3 minutes ; in about 63 per cent of the grains and 

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

 95 per cent of the grains and in more than 99 per cent 

 of the total starch in 15 minutes. (Chart D 374.) 



The hilum becomes distinct in all the grains, attended 

 by the formation of a bubble in rare grains. The lamella; 

 are moderately distinct. Gelatinization begins at the 

 hilum, which swells lightly, the starch immediately sur- 

 rounding it being cracked and broken into coarse, refrac- 

 tive granules. Two fissures extend obliquely from either 

 side of the hilum, usually to the distal margin but 

 sometimes only half of the distance between the hilum 

 and the distal margin. The portion included between 

 them becomes indistinctly granular or is seen to be 

 traversed by many indistinct, irregularly branching fis- 

 sures that divide it into refractive granules which in 

 turn gelatinize rapidly, leaving, however, a fine granu- 

 lar residue that is the last part of the grain to be dis- 

 solved. The material at the proximal end and sides, and 

 in some grains at the distal margin, forms a broad, 

 homogeneous-looking refractive band which is dissolved 

 first at one corner of the distal capsule and then separates 

 all the way around from the inner granular portion. 

 This outer portion is dissolved first and then the granular 

 inner portion. 



