TRITONIA BEGONIA. 



695 



the grains and 18 per cent of the total starch in 45 

 minutes; in about 7 per cent of the grains and 21 per 

 cent of the total starch in 60 minutes. (Chart D 501.) 



The reaction with cupric chloride begins immediately. 

 Complete gelatinization occurs in about 5 per cent of 

 the entire number of grains and 10 per cent of the total 

 starch in 5 minutes; in about 6 per cent of the grains and 

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

 7 per cent of the grains and 12 per cent of the total 

 starch in 30 minutes; in about 9 per cent of the grains 

 and 15 per cent of the total starch in 45 minutes; in 

 about the same percentage of both the grains and total 

 starch in 60 minutes. (Chart D 502.) 



The reaction with barium chloride begins in rare 

 grains in 1 minute. Complete gelatinization was not 

 observed in any of the entire number of grains and 

 0.5 per cent of the total starch in 5 minutes; still no 



complete gelatinization noted and 1 per cent of the 

 total starch in 15 minutes; very slight if any advance 

 in 30 minutes; complete gelatinization occurs in but 

 rare grains, less than 0.5 per cent of the grains and 2 

 per cent of the total starch in 45 minutes; no apparent 

 advance in 60 minutes. (Chart D 503.) 



The reaction with mercuric chloride begins in a few 

 grains immediately. Complete gelatinization occurs in 

 about 1 per cent of the entire number of grains and 

 3 per cent of the total starch in 5 minutes ; in about 2 per 

 cent of the grains and 6 per cent of the total starch in 

 15 minutes; in about 3 per cent of the grains and 9 per 

 cent of the total starch in 30 minutes; in about 4 per 

 cent of the grains and 10 per cent of the total starch 

 in 45 minutes ; in about the same percentage of the grains 

 and 11 per cent of the total starch in 60 minutes. (Chart 

 D 504.) 



11. BEGONIA. 



This genus includes about 350 species, together with 

 hundreds or thousands of garden varieties and a consider- 

 able list of hybrids. It has been divided horticulturally 

 into four groups the fibrous-rooted, semituberous, tu- 

 berous, and rex or ornamental-leaved. They are readily 

 hybridized, and members of different groups have been 

 crossed, as for instance, semituberous and tuberous, and 

 semituberous and rex. In this research the starches from 

 four sets of parent-stocks and hybrids were studied, the 

 crosses being between B. socotrana Hook, (semituberous) 

 and garden varieties of the tuberous group. B. socotrana 

 is the pollen parent in each set. The specimens were 

 obtained from the growers, James Veitch and Sons, 

 London. 



36. B. single crimson scarlet (seed parent), B. socotrana 



pollen parent), and B. inrs. heal (hybrid), page 695. 



37. B. double light rose (seed parent), B. socotrana .(pollen 



parent), and li. ensign (hybrid), page 702. 



38. B. double white (seed parent), B. socotrana (pollen 



parent), and B. Julius (hybrid), page 708. 



39. B. double dark rose (seed parent), B. socotrana (pollen 



parent), and B. success (hybrid), page 713. 



Examinations were made in full of only the first set. 

 In the other sets the reaction-intensity studies were re- 

 stricted to the reactions with polarization, iodine, gentian 

 violet, safranin, temperature of gelatinization, chloral 

 hydrate, chromic acid, pyrogallic acid, nitric acid, and 

 strontium nitrate. The limitations in the latter were 

 owing to the closeness of the reactions of the seed parents 

 in all of the remaining reactions, excepting only those 

 with cobalt nitrate, barium chloride, and mercuric 

 chloride. 



3G. STARCHES OF BEGONIA SINGLE CEIMSON SCAKLET, 



B. SOCOTRANA, AND B. MRS. HEAL. 



Starch of Begonia socotrana (pollen parent) is de- 

 scribed on pages 704 to 707. 



BEGONIA SINGLE CRIMSON SCARLET (SEED PARENT). 



(Plate 21. fig. 121; Charts D 505 to D 526.) 



HISTOLOOIC PBOPEBTIES. 



In form the grains are almost solely simple and iso- 

 lated, a compound grain or an aggregate being occasion- 

 ally seen. The compound grains belong to one type: 

 2 small grains, each consisting of a hilum and 1 or 2 



lamellae, both surrounded by 30 or more common second- 

 ary lamella?, and attached to the proximal end of a large, 

 elongated grain. The aggregates consist of 2 or 3 small, 

 equal-sized grains, linearly or pyramidally arranged. 

 The grains are moderately often irregular, and the irreg- 

 ularities are due to the following causes: (1) A set of 

 secondary lamella? whose longitudinal axis is at an angle 

 of varying size with that of the primary set; (2) 1 or 2 

 rather small rounded protuberances from the sides or 

 the proximal end; (3) a deviation of the axis and a 

 consequent bending of the grain; (4) a greater develop- 

 ment of either distal or proximal end than of the rest 

 of the grain. In many of the grains the secondary 

 formation is so much greater than the primary deposit 

 that the latter appears as a small grain embedded in the 

 proximal part of a large grain, which is often of the same 

 but not infrequently of a very different shape. The 

 conspicuous forms are rather broad elliptical, ovoid, 

 round, and nearly round. The additional forms are rod- 

 shaped, pyriform, and triangular. The few very broad 

 forms are somewhat flattened, and when viewed on edge 

 appear to have an elongated elliptical shape. 



The hilum is a rather indistinct, small, round spot 

 which is rarely fissured. When fissuring occurs, the 

 fissures have the following forms : ( 1 ) A single, short, 

 straight line transversely or obliquely placed; (2) an 

 irregularly stellate arrangement of several fissures. The 

 hilum is eccentric from 0.3 to 0.17, usually 0.25, of the 

 longitudinal axis. 



The lamella; are usually fine and not very distinct. 

 There is often one distinct, coarse, refractive lamella near 

 the hilum, and another outlining the primary grain, if 

 the grain has both primary and secondary starch for- 

 mations. In addition there are often 3 or 4 broad refrac- 

 tive lamellae which divide the fine lamelloe into bands of 

 varying breadth. The lamella? are more distinct near the 

 distal end than near the hilum, and less distinct in the 

 primary than in the secondary starch. The number on 

 the grains can not be determined. 



In size the grains vary from the smaller which are 

 4 by 4;u, to the larger which are 30 by 16/i, in length and 

 breadth. The common sizes are 20 by 13/j. and 18 by 14/*. 



Comparison of the histologic properties between B. 

 socotrana and B. single crimson scarlet shows : 



