BEGONIA. 



711 



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

 30 minutes. (Charts D 535 and D536.) A portion 

 of the margin of some grains is quite resistant, but most 

 of the grain is easily gelatinized. 



The hilum becomes distinct in all the grains, attended 

 by the formation of a bubble in a moderate minority of 

 the grains. . The lamella; are not very distinct. Gela- 

 tinization begins at the hilum which swells more rapidly 

 toward the proximal than toward the distal end. Two 

 fissures appear which extend from either side of the hilum 

 one-half to three-fourths of the distance from the hilum 

 to the distal margin, and in most grains the starch com- 

 prehended between these fissures and immediately distal 

 to the hilum is divided by a double row of slanting fissures 

 and then gelatinized, leaving a granular refractive resi- 

 due at the distal end. In the other grains the starch 

 between the fissures is not divided by fissures but gela- 

 tinizes rapidly, leaving also a small granular refractive 

 mass at the distal end. The starch at the proximal and 

 distal margins and the sides forms a thick, refractive, 

 homogeneous band which is slowly gelatinized. The 

 gelatinized grains are moderately swollen, have rather 

 thick capsules, and are usually not much distorted, but 

 sometimes vary considerably. 



Comparison of the pi/rogallic-acid reactions between 

 B. socolrana and B. double white shows: 



The hilum becomes distinct, unattended by the for- 

 mation of a bubble in any of the grains. The lamella; 

 are more distinct than in B. double while. Gelatiniza- 

 tion begins at the hilum, and the differences noted are 

 that the starch comprehended between the 2 fissures 

 from the hilum (and immediately distal to the hilum) is 

 divided by a double row of slanting fissures, which arc 

 more distinct than in B. double white, and then slowly 

 gelatinize, leaving a more distinctly granular and more 

 refractive mass at the distal end than in B. double white. 

 No further change takes place in the grain except an 

 increased refractivity. (See note, page 322.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in 100 per cent of the 

 entire number of grains and total starch in 15 seconds. 

 (Chart D537.) 



The hilum becomes distinct in all the grains, attended 

 by the formation of a bubble in the majority. The 

 lamella; are not visible. Gelatinization begins at the 

 hilum which swells very rapidly in the direction of the 

 proximal end. Two fissures extend a short distance 

 from either side of the hilum toward the distal end. 

 The starch between is not distinctly fissured, but be- 

 comes granular and gelatinizes comparatively slowly. 

 At the same time the bubble swells, then shrinks, and 

 finally disappears, accompanied by considerable invagina- 

 tion of the capsule at the sides of the proximal end. 

 The gelatinized grains are much swollen, have rather 

 thin capsules, and are somewhat distorted. 



Comparison of the nitric-acid reactions between B. 

 socotrana and B. double white shows: 



The hilum becomes distinct in all the grains unat- 

 tended by the formation of a bubble in any. The lamella 1 

 are also distinct. The hilum does not enlarge so much 

 toward the proximal end as in B. double white, and the 

 starch comprehended between the 2 fissures which ex- 

 tend from either side of the hilum nearly to the margin 



is divided by 2 rows of slanting fissures and is then 

 slowly gelatinized, leaving small pointed protuberances 

 of refractive starch projecting into the interior of the 

 swelling grain. This is as far as the reaction evejc goes 

 in the normal grains, and none of these phenomena is 

 seen in B. double white. 



The reaction with strontium nitrate begins imme- 

 diately. Complete gelatinization occurs in about 92 

 per cent of the entire number of grains and 97 per <<nt 

 of the total starch in 1 minute; in Kio per cent of the 

 grains and total starch in 2 minutes. (Chart U 538.) 



The hilum becomes distinct in all the grains, attended 

 by the formation of a bubble in a few. The lamellae 

 are moderately distinct in some grains, but in the 

 majority they are not visible. Gelatinization begins 

 at the hilum which swells rapidly, more rapidly toward 

 the proximal than toward the distal end. Two indistinct 

 fissures extend from either side of the hilum nearly to 

 the distal margin, and the starch comprehended between 

 them is fissured by rather indistinct longitudinal fis- 

 sures. This is gelatinized with moderate rapidity and 

 leaves a small refractive granular residue at the distal 

 margin. The starch at the proximal end and sides 

 forms a homogeneous-looking, refractive, marginal band 

 which is much thicker and broader at the sides than at 

 the proximal end. This grows thinner and more nearly 

 transparent and is finally gelatinized as is also the 

 irregular refractive mass at the distal end. The gela- 

 tinized grains are much swollen, have thick capsules, 

 and are somewhat distorted. 



Comparison of the stronfium-nitrate reactions be- 

 tween B. socolrana and B. double white shows: 



The hilum becomes distinct in all the grains, unat- 

 tended by the formation of a bubble in any. The lamella; 

 are always visible and are more distinct than in B. double 

 white. Gelatinization proceeds in very much the same 

 manner as in B. double while, except that the 2 fissures 

 which extend from either side of the hilum are more 

 distinct, as are also the longitudinal fissures in the 

 starch comprehended between them. This starch is also 

 often divided by a double row of slanting fissures which 

 are first seen near the hilum and then progressively 

 nearer the distal end as the grain swells and the portion 

 near the hilum is gelatinized. The gelatinized grains 

 are more swollen, do not have such thick capsules, and 

 are more distorted, particularly at the distal end, than in 

 B. double white. 



Begonia julius (Hybrid). 



(Plate 22, fig. 129; Charts D 533 to D 538.) 

 Histologic Pboperties. 

 In form the grains are usually simple and isolated, 

 but, as in B. double white, compound grains and aggre- 

 gates are occasionally seen. They both are of the same 

 types as in B. double white. The grains are usually regu- 

 lar, and have fewer irregularities than in either parent, in 

 this characteristic showing a closer relationship to B. 

 double white than to B. socotrana. The irregularities 

 which occur are due to the following causes: (1) Slight 

 deviation of the longitudinal axis and consequent bend- 

 ing of the grain ; (2) 1 or 2 large or small, rounded pro- 

 tuberances from the proximal end or sides; (3) rarely, 

 depressions and elevations of the distal end and margin 



