BEGONIA. 



713 



The reaction with chromic acid begins immediately. 

 Complete gelatinization occurs in 7 per cent of the entire 

 number of grains and 75 per cent of the total starch in 5 

 minutes ; in about 41 per cent of the grains and 90 per 

 cent of the total starch in 15 minutes; in about 95 per 

 cent of the grains and 99 per cent of the total starch in 30 

 minutes. (Chart D 534.) (See pages 697 and 705.) 



The hilum and lamella? are as distinct as in B. soco- 

 trana. Gelatinization begins at the hilum and pro- 

 gresses as in B. double white, except that the starch be- 

 tween the 2 fissures, which proceed from the hilum, is 

 more distinctly fissured and becomes more distinctly 

 granular, showing the influence of B. socotrana. There 

 is not a clearly markc'd division into an outer and an 

 inner layer as in either parent, and in this respect the 

 hybrid more closely resembles B. double white. In this 

 reaction B. Julius shows qualitatively a somewhat closer 

 relationship to B. double white than to B. socotrana. 



The reaction with pyrogallic acid begins in rare 

 grains in 30 seconds. Complete gelatinizatiou occurs in 

 less than 0.5 per cent of the entire number of grains and 

 20 per cent of the total starch in 5 minutes ; in about 7 

 per cent of the grains and 75 per cent of the total starch 

 in 15 minutes; in about 44 per cent of the grains and 

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

 58 per cent of the grains and 92 per cent of the total 

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

 grains and 95 per cent of the total starch in GO minutes. 

 (Chart D 535.) 



The hilum and lamellae are as distinct as in B. 

 socotrana, and gelatinization proceeds as in B. double 

 white, except that the starch just distal to the hilum 

 and comprehended between the 2 fissures from either 

 side of the hilum is less often divided by a double row 

 of slanting fissures, and more often simply gelatinizes 

 without any distinct fissuring or granule formation. The 

 gelatinized grains are moderately swollen, and have 

 rather thick capsules as in B. double white, but are some- 

 what more distorted than in that starch. In this reaction 

 B. Julius shows qualitatively a closer relationship to B. 

 double white than to B. socotrana. (See note, page 698.) 

 The reaction with nitric acid begins immediately. 

 Complete gelatinizatiou occurs in about 95 per cent of 

 the entire number of grains and 99 per cent of the total 

 starch in 15 seconds; in 100 per cent of the grains and 

 total starch in 30 seconds. (Chart D 537.) 



The hilum and lamellae are as distinct as in B. soco- 

 trana. Gelatinization begins at the hilum and pro- 

 gresses as in B. double white. The gelatinized grains are 

 as much swollen, and have as thin capsules as in B. 

 double white, but are somewhat more distorted than in 

 that starch. In this reaction B. Julius shows qualitatively 

 a closer relationship to B. double white than to B. 

 socotrana. 



The reaction with strontium nitrate begins in a few 

 grains immediately. Complete gelatinization occurs in 

 about 68 per cent of the entire number of grains and 

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

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

 in 2 minutes. (Chart D 538.) 



The hilum and lamellae are as distinct as in B. soco- 

 trana. Gelatinization begins at the hilum and progresses 

 in the great majority of the grains as in B. double white, 

 but in some grains a double row of slanting fissures is 

 22 



formed as in B. socotrana and gelatiuization progresses as 

 in that starch. The gelatinized grains are as much swol- 

 len, have as thick capsules, and are as much distorted as in 

 B. double white. In this reaction B. Julius shows, quali- 

 tatively, a closer relationship to B. double white than to 

 B. socolrana. 



39. STARCHES OF BEGONIA DOUBLE DEEP ROSE, B. 



SOCOTRANA, AND B. SUCCESS. 



Starch of Begonia socotrana (pollen parent) is de- 

 scribed on pages 704 to 707. 



BEGONIA DOUBLE DEEP ROSE (SEED PARENT). 



(Plate 22, fig. 130; Charts D 539 to D 544.) 



HISTOLOGIC PROPERTIES. 



In form the grains are usually simple and isolated. 

 A few compound grains are seen, and also a number of 

 small single grains with pressure facets on their distal 

 ends, indicating the previous existence of aggregates. 

 The compound grains belong to two types: (1)2 grains, 

 each consisting of a hilum and 3 or 4 lamellae, surrounded 

 by '. ; to 3 common secondary lamella 1 , and located at the 

 middle of a common-sized grain; (2) 2 grains each 

 consisting of a hilum and 1 or 2 lamellae surrounded by 

 12 to 18 common secondary lamellae and attached to 

 the proximal end of a somewhat elongated grain. A small 

 majority of the grains are somewhat irregular, and the 

 irregularities are due to the following causes: (1) A sec- 

 ondary set of lamellae whose longitudinal axis is at an 

 angle of varying size with that of the primary set. Some- 

 times, some at least of the secondary lamellae completely 

 encircle the primary grain, and in other grains they are 

 merely applied to one side of the primary grain ; (2) 

 wide, shallow depressions in the margin; (3) small 

 rounded protuberances from the sides or from either end ; 

 (4) 1 or 2 pressure facets at the distal end; (5) a slight 

 deviation of the axis with a consequent bending of the 

 grain. The conspicuous forms are ovoid, round, and 

 nearly round. The additional forms are triangular, reni- 

 form, dome-shaped, quadrilateral, and lenticular. The 

 broader grains are somewhat flattened and when seen on 

 edge have an elongated elliptical or ovoid form. 



The hilum is not a very distinct, small, round spot. 

 It is very rarely fissured, and the fissures have the follow- 

 ing forms: (1) A very small, straight, transverse line; 

 (2) an irregularly stellate arrangement of short fissures. 

 The hilum is eccentric from 0.42 to 0.21, usually 0.2G, 

 of the longitudinal axis. 



The lamella; are usually very distinct and rather 

 coarse. Those near the hilum are not so distinct and not 

 so coarse as those near the distal end, and those compos- 

 ing the primary grains are not so distinct nor so coarse as 

 those composing the secondary starch. Near the hilum 

 they are round and continuous, and throughout the rest 

 of the grain they have in general the form of the outline 

 of the grain, but are often wavy. There is usually 1 

 broad, very refractive lamella near the hilum. If the 

 grain contains both primary and secondary starch the 

 two deposits are separated by a broad refractive lamella. 

 The number counted on the larger grains varies from 

 16 to 30, usually 22, much less than in B. socotrana. 



In size the grains vary from the smaller which are 

 10 by 10/A, to the larger elongated grains which are 34 

 by 24/*, and the larger broader grains which are 30 by 



