704 



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



the distal end. The gelatinized grains are much swollen, 

 have rather thick capsules, and are somewhat distorted. 



The reaction with strontium nitrate begins imme- 

 diately. Complete gelatinization occurs in about 62 

 per cent of the entire number of grains and 77 per cent 

 of the total starch in 1 minute ; in about 96 per cent of 

 the entire number of grains and 98 per cent of the total 

 starch in 2 minutes. (Chart D 532.) 



The hilum becomes distinct in all the grains, un- 

 attended by the formation of a bubble in any. The 

 lamellae become moderately distinct. Gelatioization be- 

 gins at the hilum which swells rapidly more in the direc- 

 tion of the proximal than of the distal end. Two fissures 

 are sometimes seen to extend from either side of the 

 hilum about three-fourths of the distance from the hilum 

 to the distal margin and, if these are present, the starch 

 comprehended between them is indistinctly fissured and 

 gelatinizes rapidly, leaving only a small, irregular, refrac- 

 tive residue at the distal end. If the 2 fissures are not 

 present there is no other fissuring visible in the grain. 

 The hilum swells, and a broad, refractive, homogeneous- 

 looking band is formed at the margin which is much 

 broader at the distal than at the proximal end of the 

 grain. In both cases as the grain swells two deep in- 

 vaginations of the capsule occur which are later straight- 

 ened out. The gelatinized grains are much swollen, have 

 moderately thick capsules, and are somewhat distorted. 



STARCH OF BEGONIA SOCOTRANA (POLLEN PARENT). 



(Plates 21 and 22, figs. 122, 125, 128, and 131; Charts D 505 

 to D 520.) 



HISTOLOOIC PROPERTIES. 



In form the grains are always simple and isolated. 

 Not even a few aggregates are seen as in B. double light 

 rose. The grains are usually regular, but irregularities 

 occur much more frequently than in B. double light' rose. 

 Irregularities are due to the following causes: (1) Most 

 frequently, 1, 2, or more, large rounded or pointed protu- 

 berances from the proximal end or sides; (2) a greater 

 development of one part of the distal end of the grain 

 than of the rest; (3) a deviation of the axis and a conse- 

 quent bending of the grain; (4) rarely, elevations and 

 depressions of the distal end, producing in some grains 

 a somewhat fluted appearance; (5) rarely a secondary set 

 of lamellae whose axis is at an angle with that of the pri- 

 mary set. The conspicuous forms are long, slender ovoid, 

 and elliptical, the latter sometimes with flattened distal 

 end. The additional forms are irregularly quadrilateral 

 with rounded angles, irregularly boot-shaped, rod-shaped, 

 club-shaped, and triangular. Some of the grains of this 

 specimen are much sharpened at the distal end as if 

 eroded. The grains, as in B. double light rose, are usually 

 not flattened, but some of the rare broad forms are some- 

 what flattened, and when seen on edge have an ovoid 

 shape. 



The hilum is somewhat less distinct and somewhat 

 more often fissured than in B. double light rose, but not 

 in the majority of the grains. The fissures have the fol- 

 lowing forms : (1) A single, straight, or curved line trans- 

 versely or obliquely placed; (2) a somewhat branched 

 Y-shape; (3) rarely, an irregularly stellate arrangement 

 of several fissures; (4) rarely, a flying-bird form. The 

 hilum is apparently never centric, and is more eccentric 

 than in B. double light rose. It is eccentric from 0.3 to 



0.15, usually 0.18, of the longitudinal axis, which is 0.13 

 more eccentric than in B. double light rose. 



The lamellae are fine and not so distinct as in B. double 

 light rose. Near the hilum they are round and con- 

 tinuous, and in the rest of the grain are discontinuous 

 and follow the form of the contour of the grain, but show 

 an occasional waviness of outline. The lamellae are 

 always more distinct at the distal than at the proximal 

 end, instead of sometimes more distinct at the proximal 

 than at the distal end, as in B. double light rose. There 

 are often 1 to 3 or more broad refractive lamellae situated 

 about half the distance from the hilum to the distal 

 margin. The number counted on the larger grains varies 

 from 28 to 38, usually 33, more numerous than in B. 

 double light rose. 



In size the grains vary from the smaller which are 

 10 by 6/u, to the larger which are 52 by 22/t, in length 

 and breadth. The common sizes are 30 by 21/i and 32 by 

 14/t, larger than in B. double light rose. 



POLARISCOPIC PROPERTIES. 



The figure is distinct and is either moderately or very 

 well defined. The lines always cross at an acute angle 

 which varies considerably in size in the different grains, 

 much more than in B. double light rose. They are 

 usually not so thick as in B. double light rose, and are 

 much less frequently bent, but more often bisected. 



The degree of polarization varies from moderate to 

 moderately high (value 60), 10 units less than in B. 

 double light rose. There is some variation in a given 

 aspect of a few grains. This is not seen at all in B. double 

 light rose. 



With selenite the quadrants are moderately to very 

 clear-cut. They are more unequal in size than in B. 

 double light rose and somewhat less often irregular in 

 shape. The colors are often not so pure as in B. double 

 light rose, and there is a much smaller number of grains 

 which have a greenish tinge. 



IODINE REACTIONS. 



With 0.25 per cent Lugol's solution the grains all 

 color a light violet (value 30), 15 units less than in 

 B. double light rose; the color deepens rather slowly and 

 at the same time assumes more of a bluish tint, until it is 

 moderately deep. With 0.125 per cent Lugol's solution, 

 the grains all color a very light violet, much less than 

 in B. double lig'ht rose, and the color deepens slowly 

 until it is moderate and has assumed a somewhat bluish 

 tint. After heating in water until the grains are all gela- 

 tinized and then treating with a 2 per cent Lugol's solu- 

 tion, the gelatinized grains are all colored a moderately 

 light to deep blue tinged with violet, more than in B. 

 double light rose; and the solution a deep indigo-blue, 

 less than in B. double light rose. If the preparation 

 is boiled for 2 minutes and then treated with an excess 

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

 color a moderate indigo at the proximal end more than 

 in B. double light rose; the capsules a very deep violet, 

 deeper than in B. double light rose; and the solution 

 a very deep indigo blue, as in B. double light rose. 



ANILINE REACTIONS. 



With gentian violet the grains all color lightly at once, 

 and in 30 minutes they are lightly to moderately colored 

 (value 35), 5 units less than in B. double light rose. 



