750 



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



apparently related to the difference in the contour of the 

 sides. The eccentricity of the hilum varies from 0.44 to 

 0.11, commonly 0.25 to 0.16, of the longitudinal axis. 



The lamella in the smaller and medium-sized grains 

 are frequently indistinct, with the exception of one which 

 is moderately coarse and refractive; but in the larger 

 grains they can usually be observed over the greater part 

 of the grain, and are moderately fine with the exception 

 of 1 or 2 which are broader and often quite refractive. 

 They are frequently less distinct for about one-third of 

 the distance from the hilum, although in some grains 

 either a circular or lenticular ring may be detected around 

 the hilum ; over most of the grain, however, they closely 

 follow the outline, becoming flattened or irregular toward 

 the distal end, according to the character of the grain 

 at that margin. A refractive band in which the lamellae 

 are usually indistinct is frequently found separated from 

 the main body of the grain by a moderately coarse and 

 quite refractive lamella. This refractive band may 

 form either a border around the entire grain or a band 

 across the distal margin which may extend unilaterally 

 toward the proximal end. In some moderate-sized, ellip- 

 soidal grains this band may form a marginal border with 

 lateral extension at the distal margin, not infrequently 

 being greater at one corner than the other ; the lamellae 

 in this case, while fine, are generally demonstrable. The 

 bands above noted probably represent a secondary set of 

 lamellae. A secondary set of lamellae placed at about 

 a right angle to the primary set is occasionally observed. 

 The direction of the lamellae is occasionally shifted, and 

 since there is not always a definite line of demarcation 

 such as one coarser refractive lamella or a change in the 

 character either from fine to coarse or in the degree of 

 refractivity, it could not be determined whether or not 

 this is caused by depositions at different periods or by a 

 change in the longitudinal axis during one period. 



The size of the grains varies from the smaller which 

 are 4 by 3^, to the larger which are 36 by 24/t, com- 

 monly about 24 by 18/*, in length and breadth. 



POLABISCOPIC PROPERTIES. 



The figure is clean-cut and varies from centric to 

 quite eccentric, with a larger pro-portion of the eccentric 

 type. The lines are usually fine and generally intersect 

 either at a right angle or obliquely, but sometimes are 

 so arranged as to form an elongated, median line with 

 bisected ends. The lines may be straight, but are fre- 

 quently bent and sometimes bisected. Double and mul- 

 tiple figures are moderately common, consisting of both 

 the aggregate and compound type. 



The degree of polarization is high to very high (value 

 85). A few grains show a variation in the same aspect 

 of a given grain. 



With selenite the quadrants are usually sharply de- 

 fined, generally unequal in size, and frequently slightly 

 irregular in shape. The colors are generally pure, but 

 occasionally impurity appears at both ends of the scale, 

 namely orange and purplish, and with a greenish tinge to 

 both colors. 



IODINE REACTIONS. 



With 0.25 per cent Lugol's solution the grains color a 

 moderate blue-violet (value 55), which deepens rapidly 

 to a very deep blue. With 0.125 per cent Lugol's solution 

 the grains color a light blue-violet, which deepens rapidly 



and becomes bluer in tint ; there is more variation in the 

 depth of the individual grains with this solution than 

 with the former. After heating in water until all the 

 grains are gelatinized and then adding 2 per cent Lugol's 

 solution, most of the grains color a moderately deep blue, 

 some with a slight reddish tint, and the solution a moder- 

 ately deep blue with slight greenish tint. If the prepara- 

 tion is boiled for 2 minutes and then treated with an 

 excess of 2 per cent Lugol's solution, the grain-residues 

 (which are very few in number) color a light to moderate 

 blue with reddish tint, and most of the capsules a deep 

 old-rose to wine-red, a few amethyst or reddish-heliotrope, 

 and the solution a deep blue. 



ANILINE REACTIONS. 



With gentian violet the grains color very lightly at 

 once, and in 30 minutes they are moderately stained, with 

 rare grains moderately deep (value 50). One lamella is 

 often deeper in color than the rest of the grain, sometimes 

 the border distal to it being lighter than the main body 

 of the grain. 



With safranin the grains immediately stain lightly, 

 a little deeper than with gentian violet, and in half an 

 hour they are moderate to moderately deep in color 

 (value 55), a little deeper than with gentian violet. The 

 same variation in the depth of 1 lamella is noted as with 

 gentian violet. 



TEMPERATURE REACTIONS. 



The temperature of gelatinization of the majority 

 of grains is at 70 to 71 C., and of all but rare resistant 

 grains at 73 to 74 C., mean 73.5 C. The mesial 

 portion of the grain is much less resistant than a few 

 marginal lamellae ; this central portion being gelatinized 

 in practically all the grains at G5 to 67 C., but the mar- 

 ginal lamellae resist the process until the temperature 

 of 73 to 74 C. is reached. 



EFFECTS OF VARIOUS REAGENTS. 



The reaction with chloral hydrate begins immediately. 

 Complete gelatinization occurs in about 51 per cent of 

 the entire number of grains and 67 per cent of the total 

 starch in 5 minutes; in about 75 per cent of the grains 

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

 about 87 per cent of the grains and 97 per cent of the 

 total starch in 30 minutes ; in about 90 per cent of the 

 grains and 98 per cent of the total starch in 45 minutes ; 

 little if any further advance in 60 minutes. (Chart 

 D595.) 



The hilum becomes distinct, and sometimes a bubble 

 is formed there. The lamellae are distinct at first, but 

 later become obscured. A broad refractive space forms 

 at the distal margin, but does not extend completely 

 around the grain. Gelatinization begins in most grains at 

 the distal margin by means of small cracks that invade 

 the grain from the margin ; this is followed in many 

 grains by swelling of the hilum and rapid gelatinization 

 of the proximal end. In other grains the proximal end 

 is not affected until the end of the reaction, and in still 

 others the proximal end is affected first and the distal 

 end last. In the first method, gelatinization proceeds 

 rather unevenly from the initial points, the grain assum- 

 ing a pitted and often a granular appearance just pre- 

 ceding gelatinization, and granules are separated from 

 this mass and gelatinized. Usually the margin is less 



