716 



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



nearly transparent until it is completely gelatinized. 

 The gelatinized grains are moderately swollen, have 

 thick capsules, and are somewhat distorted. 



Comparison of the pyrogallic-acid reactions between 

 B. socotrana and B. double deep rose shows: 



The hilum and lamellae are both somewhat more dis- 

 tinct than in B. double deep rose. The method of 

 gelatinization differs somewhat from that described for 

 B. double deep rose in the following points : Two fissures 

 which extend from the hilum on either side are much 

 shorter; the starch comprehended between them is 

 divided by a double row of slanting fissures which are 

 very distinct; when this part of the grain is gelatinized 

 it leaves a refractive distinctly granular mass at the distal 

 end ; and the band formed from the starch at the margin 

 is lamellated instead of being homogeneous in appear- 

 ance. No further change occurs after the gelatinization 

 of the distal material and the formation of a marginal 

 band. (See note, page 698.) 



The reaction with nitric acid begins immediately. 

 Complete gelatinization occurs in 100 per cent of the 

 grains and total starch in 15 seconds. (Chart D 543.) 



The hilum becomes distinct in all the grains, attended 

 by the formation of a bubble in a moderate number of 

 grains. The lamellae are not very distinct, but are visi- 

 ble. Gelatinization begins at the hilum, which enlarges 

 more rapidly toward the proximal end than toward the 

 distal end. Two fissures proceed from the hilum on 

 either side and extend nearly to the distal margin, and the 

 starch comprehended between these 2 fissures becomes 

 irregularly granular and is rapidly gelatinized. The 

 starch at the proximal and distal margins and sides 

 forms a rather thin, refractive, homogeneous-looking 

 band around the margin and this is gelatinized rather 

 slowly. 



The gelatinized grains are much swollen, have rather 

 thin capsules, and are often considerably distorted. 



Comparison of the nitric-acid reactions between B. 

 socotrana and B. double deep rose shows : 



The hilum becomes more distinct in all the grains 

 than in B. double deep rose, but this is not attended 

 by the formation of a bubble in arty of the grains. The 

 lamellae also are much more distinct than in B. double 

 deep rose. Gelatinization begins at the hilum which 

 swells slightly, and it progresses very differently from 

 that in B. double deep rose. The starch comprehended 

 between the 2 fissures which extend from either side of 

 the hilum is first divided by 2 rather indistinct rows of 

 slanting fissures which become more and more distinct as 

 gelatinization proceeds. This starch is slowly gelatin- 

 ized, leaving small, pointed protuberances of refractive 

 starch projecting from the sides into the center of the 

 swelling grains. This is as far as the reaction even seems 

 to go in the normal grains. 



The reaction with strontium nitrate begins imme- 

 diately. Complete gelatinization occurs in about 44 per 

 cent of the entire number of grains and 80 per cent of the 

 total starch in 1 minute; in about 98 per cent of the 

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

 in 2 minutes. (Chart D 544.) 



The hilum becomes distinct, unattended by the forma- 

 tion of a bubble in any of the grains. The lamella; are 

 distinct. Gelatinization begins at the hilum which 

 swells somewhat, and two fissures proceed from either 



side of the hilum to only about half the distance between 

 the hilum and the distal margin. The starch compre- 

 hended between these 2 fissures is indistinctly fissured 

 near the hilum, and the distal end is also invaded by 

 a number of longitudinal fissures which extend inward 

 from the margin. The starch thus fissured becomes 

 granular and is then gelatinized rapidly. The hilum 

 meanwhile has been swelling rapidly, more toward the 

 proximal than toward the distal end of the grain. The 

 starch at the proximal end and sides forms at the margin 

 a thick, indistinctly lamellated band which gradually 

 grows thinner and more nearly transparent until it is 

 gelatinized. As the granular distal portion of the grain is 

 gelatinized there is an invagination of the capsule at the 

 proximal end, which is, however, straightened out later. 

 The gelatinized grains are much swollen, have thick cap- 

 sules, and are not greatly distorted. 



Comparison of the strontium-nitrate reactions be- 

 tween B. socotrana and B. double deep rose shows : 



The hilum and lamella? are more distinct than in B. 

 double deep rose. Gelatinization begins at the hilum 

 and proceeds much the same as in B. double deep rose, 

 except that the 2 fissures from the hilum are more distinct 

 and longer; the starch between them is not fissured by 

 longitudinal fissures from the distal end, but only from 

 the hilum; and it is also often fissured by a double row 

 of slanting fissures which are never seen in B. double 

 deep rose; and the starch at the proximal end is never 

 observed to be invaginated during the gelatinization of 

 the distal starch. The gelatinized grains are as much 

 swollen, do not have such thick capsules, and are some- 

 what more distorted, especially at the distal end, than in 

 B. double deep rose. 



Begonia success (Hybrid). 



(Plate 22, fig. 132; Charts D 539 to D 544.) 

 Histologic Properties. 



In form the grains are always simple as in B. soco- 

 trana, and are usually isolated, but a few aggregates are 

 seen which may be doublets or quadruplets arranged in a 

 somewhat irregular mass. The grains are more regular 

 in form than in either parent, in this respect more closely 

 resembling B. socotrana, but the character of the irregu- 

 larities is closer to B. double deep rose, except that sec- 

 ondary sets of lamellae are of rare occurrence. Irregulari- 

 ties are due to the following: (1) A deviation of the axis 

 and consequent bending of the grain; (2) a greater de- 

 velopment of one part of the distal end than of the rest; 

 (3) shallow depressions in the margin; (4) rounded pro- 

 tuberances from either end or side ; (5) a secondary set of 

 lamellfc whose longitudinal axis is at an angle of varying 

 size with that of the primary set; (6) 1 or 2 pressure 

 facets at the distal end. The conspicuous forms are elon- 

 gated elliptical with flattened distal end, ovoid, and 

 nearly round. The additional forms are round, rod- 

 shaped, club-shaped, triangular, and irregularly quadri- 

 lateral. The broad forms, as in both parents, are some- 

 what flattened, and when viewed on edge have an 

 elongated elliptical or ovoid shape. In form B. success 

 shows a closer relationship to B. socotrana than to B. 

 double deep rose. 



The hilum is not very distinct, as in both parents. 

 It is very rarely fissured, as in B. double deep rose, and 

 the fissures have the same forms as in that starch. The 



