124 



HISTOLOGIC PROPERTIES AND REACTIONS. 



Yiu.ocity-reaction Curves. 



This section treats of the velocity-reaction curves of 

 the starches of Begonia double deep rose, B. socotrana, 

 and B. success, showing quantitative differences in the 

 behavior toward different reagents at definite time-inter- 

 vals. (Charts D 539 to D544.) 



These charts differ from those of the last set chiefly 

 in the reversal of the relative positions of the curves of 

 the seed parent and hybrid and the more marked close- 

 ness of these curves in the pyrogallic-acid reaction. The 

 nitric-acid and strontiunmitrate curves are in the two 

 sets in each case practically the same. 



Reaction-intensities of the Hybrid. 



This section treats of the reaction-intensities of the 

 hybrid as regards sameness, intermediateness, excess, and 

 deficit in Telation to the parents. (Table A 39 and 

 Chan- D539 t<> D544.) 



The reactivities of the hybrid are the same as those 

 of the seed parent in the reactions with safranin and 

 nitric acid ; the same as those of the pollen parent with 

 polarization, iodine, and gentian violet; the same as 

 those of both parents in none; intermediate with tem- 

 perature and chloral hydrate, in both heing closer to those 

 of the seed parent ; highest with chromic acid, pyrogallic 

 acid, and strontium nitrate, in all three heing closer to 

 those of the seed parent ; and the lowest in none. 



The following is a summary of the reaction-intensi- 

 ties: Same as seed parent, 2; same as pollen parent, 3; 

 same as both parents, 0; intermediate, 2; highest, 3; 

 lowest, ii. 



In these !'• u read ions the tendencies seem to be about 



equal to sameness as one or the other parent, intermedi- 



ess and highest reactivity; but the influences of the 



seed parent in determining the properties of the starch of 



the hybrid distinctly dominate those of the other parent. 



Composite Curves of tin: Reai tion-intensities. 



Tin :i treats of the composite curves of the 



reaction intensities, showing the differentiation of the 

 starches of Begonia double deep r<>se. /.'. socotrana, and 

 /;. success. (Chart E 39.) 



The most conspicuous features of this chart are: 



( 1 ) The generally close correspondence of all three 

 curves, although in some instances the curves are well 

 separated, as in the preceding set-. 



( 2 | The higher position of the curve of B. double 

 deep rose in the relation to the curve of the other parent 

 in the reactions with iodine, gentian violet, safranin, 

 temperature, chloral hydrate, chromic acid, pyrogallic 

 acid, and strontium nitrate; the lower position with 

 polarization; and the identical position with nitric acid. 



(3) The varying position of the hybrid curve in rela- 

 tion to the parental curves. It is the same or practically 

 the same as the curve of B. double deep rose in the i 

 tions with safranin, temperature, chromic acid, pyrogallic 

 acid, and strontium nitrate; the same as that of H. soco- 

 trana in those with polarization, iodine, and gentian 

 violet; the same as the curves of both parents in that 

 with nitric acid; and intermediate in that with chloral 

 hydrate. 



Notes on the Begonias. 



The most conspicuous features of these records are 

 observed in the very definite and commonly wide differ- 

 ences between the properties of the seed parents on the 

 one hand and of Begonia socotrana, the pollen parent, 

 on the other, representing two quite different groups of 

 begonias. Histologically, the starches of the seed parents 

 have characters in common which definitely group them 

 from the starch of B. socotrana. Even far greater distini 

 tions are seen in the records of the temperatures of 

 gelatinization and of the quantitative reactions with hy- 

 drochloric acid, potassium iodide, potassium sulphocya- 

 nate, sodium hydroxide, sodium sulphide, calcium 

 nitrate, uranium nitrate, strontium nitrate, copper ni- 

 trate, cupric chloride, and mercuric chloride. The very 

 large differences in the temperature reactions of the two 

 groups exceed any records thus far made of members 

 of any genus. The least difference between members 

 of the tuberous group and B. socotrana is 11.4°, the 

 greatest 18.65°, and the average 14.85°. Such differ- 

 ences indicate corresponding marked physico-chemical 

 peculiarities of the starch molecules and prepare one for 

 finding similar diversities in the reactions with vario .s 

 chemical reagents. Comparisons of the data of the four 

 seed parents indicate well-separated horticultural or 

 subgeneric specimens. Inasmuch as B. socotrana is the 

 pollen parent in each set, it is of exceptional interest to 

 learn to what extent and in what directions the charac- 

 ters of the hybrids are influenced by this parent. Inas- 

 much as the seed parents exhiliil among themselves dis- 

 tinctive peculiarities it is to he expected that the hybrid 

 in any set will be definitely different from the hybrids 

 of the other sets, and such has been found to be a fact. 

 The hybrids show marked variability in their relations to 

 their parents, each exhibiting character- that arc either 

 common to both parents or individually parental, and in 

 varying degrees of development, sometimes being like 

 one parent or the other, or identical with both or having 

 development beyond parental extremes in one direction 

 or the other. While the inclination of the hybrid is, on 

 the whole, very definitely toward, even at times exceeding, 

 the development of the seed parent the influences of B. 



socotrana are themselves sometimes so potent that theseed 

 parent seems to be without effect. 



