122 



HISTOLOGIC PROPERTIES AND REACTIONS. 



starches of Begonia double light rose, B. socotrana, and 

 B. ensign. (Chart E 37.) 



The most conspicuous features of this chart are : The 

 generally close correspondence in the courses of the three 

 curves, although in some instances the curves are well 

 separated. The higher position of the curve of B. double 

 light rose in relation to that of B. socotrana throughout 

 excepting in the nitric-acid reaction, in which the curves 

 are the same. The varying relationship of the hybrid 

 curve to the parental curves. It is intermediate in the 

 reactions with polarization, iodine, temperature, chromic 

 acid, and pyrogallic acid ; lower than the parental curves 

 in those with gentian violet and safranin; the same or 

 nearly the same as that of B. double light rose in those 

 with chloral hydrate and strontium nitrate; and the same 

 as both parents in that with nitric acid. 



38. COMPARISONS OF THE STARCHES OF BEGONIA 

 DOUBLE WHITE, B. SOCOTRANA, AND B. JULIUS. 



In the histologic characteristics, polariscopic figures, 

 reactions with selenite, reactions with iodine, and quali- 

 tative reactions with various chemical reagents all three 

 starches have properties in common in varying degrees 

 of development, together with individualities, which col- 

 lectively in each case serve to be distinctive. The 

 starch of Begonia socotrana in comparison with that 

 of B. double white shows an absence of compounds and 

 aggregates; more irregularity of the grains and some 

 marked differences in the causes of the irregularities; 

 grains often elongated; and comparatively few round 

 and triangular forms. The hilum is less distinct, much 

 less often fissured, shows an absence of certain forms 

 of fissuration, and eccentricity is more. The lamella? 

 are finer but not so distinct, there is an absence of two 

 lamellae which are quite conspicuous in the other parent ; 

 they are more often not regular and show waviness ; and 

 they are slightly less numerous. In size the grains are 

 somewhat larger and more slender. In the polariscopic, 

 selenite and qualitative iodine reactions there are many 

 differences. In the qualitative reactions with chloral hy- 

 drate, chromic acid, pyrogallic acid, nitric acid, and stron- 

 tium nitrate the differences are numerous and some of 

 them quite individualize the parent. The starch of the 

 hybrid is more closely related to B. double white in form, 

 character and arrangement of the lamellae, and size of 

 the grains; nearer to B. socotrana in the characters of 

 the irregularities of the grains and in the character and 

 eccentricity of the hilum ; and it has fewer irregularities 

 than either parent. In the polarization figures it re- 

 sembles both parents equally. In the iodine reactions 

 the heated grains more closely resemble those of B. 

 double white, while the unheated grains more closely re- 

 semble those of B. socotrana. In the qualitative reac- 

 tions with chloral hydrate, chromic acid, pyrogallic acid, 

 nitric acid, and strontium nitrate peculiarities of both 

 parents are manifest, but the reactions, as a whole, more 

 closely resemble those of B. double white than of B. 

 socotrana. 



Reaction-intensities Expressed by Light, Color, and Tempera- 

 ture Reactions. 

 Polarization: 



B. double white, low to moderately high, value 55. 



B. Bocotrana, moderate to moderately high, higher than in B. double 

 white, value 00. 



H Julius, moderate to moderately, the same aa in B. double white, 

 value 60. 



Iodine : 



B. double white, light, value 25. 



B. socotrana, light to moderate, deeper than in B. double white, 



value 30. 



B. Julius, light to moderate, deeper than in either parent, value 40. 

 Gentian violet: 



B. double white, light to moderate, value 30. 



B. socotrana, light to moderate, deeper than in B. double white, 



value 35. 

 B. Julius, moderate to moderately deep, deeper than in cither 



parent, value 45. 

 Safranin : 



B. double white, light to moderate, value 40. 



B. socotrana, moderate, much deeper than in B. double white, 



value 55. 



B. Julius, moderately deep, deeper than in either parent, value GO. 

 Temperature : 



B. double white, in the majority at GO to 61.5, in all at 65 to 66.5, 



mean 62.75. 

 B. socotrana, in the majority at 79 to 80, in all at 81 to 81.8, 



mean 81.4. 

 B. Julius, in the majority at 65 to 66, in all at 67 to 69, mean 68 



The reactivity of B. double white is lower than that 

 of the other parent in the polarization, gentian-violet, 

 and safranin reactions, and higher in the temperature 

 reaction. The reactivity of the hybrid is the same or 

 practically the same as that of B. socotrana in the polari- 

 zation reactions ; highest of the three in those with iodine, 

 gentian violet, and safranin ; and intermediate in that 

 with temperature. The hybrid is closer to B. double 

 white than to B. socotrana in the temperature reaction ; 

 and the reverse in those with polarization, iodine, gentian 

 violet, and safranin. 



Table A 39 shows the reaction-intensities in percent- 

 ages of total starch gelatinized at definite intervals (sec- 

 onds and minutes) : 



TABLE A 38. 



VELOCITY-REACTION CURVES. 



This section treats of the velocity-reaction curves of 

 the starches of Begonia double white, B. socotrana, and B. 

 Julius, showing quantitative differences in the behavior 

 toward different reagents at definite time-intervals. 

 (Charts D 533 to D538.) 



These charts bear close resemblances to the corre- 

 sponding charts in the preceding set, but the differences 

 are sufficient to show that there are differences in parent- 

 age and offspring. There is a tendency in this set to a 



