128 



H1STOLOGIC PROPERTIES AND REACTIONS. 



stances to be well separated from the curve of M. arnold- 

 iana. The tendency for the hybrid reactions throughout 

 (excepting those with nitric acid, sulphuric acid, and po- 

 tassium hydroxide which are so rapid that no satisfac- 

 tory differentiation can be made, and in that with pyro- 

 gallic acid, in which the curve is practically identical 

 with that of the pollen parent), to be lower than that in 

 either parent; and also to show a distinctly closer rela- 

 tionship to M. gilletii than to M. arnoldiana. 



(3) The considerable differences in the interrelations 

 of the three curves: Thus, in the reactions with chloral 

 hydrate, chromic acid, sodium salicylate, calcium ni- 

 trate, uranium nitrate, strontium nitrate, and barium 

 chloride the curves are quite evenly separated, the 

 curve of M. gittetii in each chart being between the 

 curves of M. arnoldiana and the hybrid. In the reac- 

 tions with pyrogallic acid, nitric acid, potassium iodide, 

 potassium sulphocyanate, potassium sulphide, sodium 

 hydroxide, sodium sulphide, cobalt nitrate, copper ni- 

 trate, cupric chloride, and mercuric chloride there is 

 an obvious pairing of the curves of M. gilletii and the 

 hybrid, the curves being to more or less marked de- 

 grees separated from the curve of M. arnoldiana, and 

 from each other, excepting in the latter in the pyrogallic- 

 acid reactions, where the curves of M. gilletii and the 

 hybrid are practically identical. In the reactions with 

 nitric acid, potassium iodide, and sodium hydroxide the 

 only important differences are noted at the very begin- 

 ning of gelatinization. In the other reactions, with the 

 exceptions noted, while the curves tend in general to run 

 closely, there are sufficient differences to permit of 

 diagnosis. 



(4) An early period of resistance is noted in very 

 few of the reactions. In fact, there is generally a marked 

 tendency for an immediate high to very high degree of 

 reactivity which may be followed by a progressively les- 

 sening. An early period of resistance is seen in the 

 reactions of chromic acid with M. hybrida, of pyrogallic 

 acid, and, particularly, of barium chloride, with both 

 M. gilletii and M . hybrida. 



(5) The earliest period during the 60 minutes of 

 observation at which the curves are best separated for 

 the differentiation of the three starches is variable with 

 the different reagents. In case of the very rapid reac- 

 tions, including those with nitric acid, sulphuric acid, 

 hydrochloric acid, potassium hydroxide, potassium 

 iodide, potassium sulphocyanate, potassium sulphide, 

 and sodium hydroxide, the period is noted within the 

 first minute of the reactions; in those with chromic 

 acid, pyrogallic acid, sodium sulphide, sodium salicylate, 

 calcium nitrate, uranium nitrate, strontium nitrate, cal- 

 cium nitrate, copper nitrate, cupric chloride, and mer- 

 curic chloride within 5 minutes; and in those with 

 chloral hydrate and barium chloride within 15 minutes. 

 From this data the best period for the differentiation of 

 members of this genus would be, perhaps, on the whole, 5 

 minutes after the beginning of the reaction ; or better, 

 to use in most cases weaker reagents. 



REACTION-INTENSITIES OF THE HYBRID. 



This section treats of the reaction-intensities of the 

 hybrid as regards sameness, intermediateness, excess, and 

 deficit in relation to the parents. (Table A 41 and 

 Charts D 553 to D 573.) 



The reactivities of the hybrid are the same as those 

 of the seed parent in no reaction; the same as those of 

 the pollen parent in the reactions with iodine, gentian 

 violet, safranin, and pyrogallic acid; the same as those of 

 both parents in none; intermediate with hydrochloric 

 acid, and potassium hydroxide, being closer to the pollen 

 parent in one and mid-intermediate in the other ; highest 

 in none; and the lowest with polarization, temperature, 

 chloral hydrate, chromic acid, nitric acid, sulphuric acid, 

 potassium iodide, potassium sulphocyanate, potassium 

 sulphide, sodium hydroxide, sodium sulphide, sodium 

 salicylate, calcium nitrate, uranium nitrate, strontium 

 nitrate, cobalt nitrate, copper nitrate, cupric chloride, 

 barium chloride, and mercuric chloride, in all of which 

 being closer to the pollen parent. 



The following is a summary of the reaction-intensi- 

 ties : Same as seed parent, ; same as pollen parent, 4 ; 

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

 lowest, 20. 



Lowest reactivity of the three starches and sameness 

 and inclination to the pollen parent are two features that 

 stand out with marked conspicuousness. The pollen 

 parent seems to have been pre-eminent in determining 

 the characters of the starch of the hybrid, inasmuch as in 

 25 of the 26 reactions this parent bears the closer rela- 

 tionship to the hybrid, while in the remaining reaction 

 there is mid-intermediateness, but of doubtful valuation. 



COMPOSITE CURVES OF THE REACTION-INTENSITIES. 



This section treats of the composite curves of the 

 reaction-intensities, showing the differentiation of the 

 starches of Musa arnoldiana, M. gilletii, and M. hybrida. 

 ( Chart E 41.) 



The most conspicuous features of the chart are : The 

 general correspondence in the ups and downs of the 

 curves, excepting in the case of M. arnoldiana in many 

 reactions which occur so rapidly that differences are not 

 satisfactorily demonstrated. The three curves from the 

 polarization to the sulphuric acid reactions are in close 

 accord, but from the latter on to the sodium-sulphide 

 reaction the curve of M. arnoldiana shows practically 

 no change, and from then on such alterations as are 

 exhibited occur within the 5-minute limit, excepting in 

 the barium-chloride reaction, in which the limit is ex- 

 tended to 15 minutes. With M. gilletii and M. hybrida, 

 however, the variations from reagent to reagent are com- 

 monly well marked. With somewhat weaker reagents the 

 curve of M. arnoldiana would in all probability corre- 

 spond in its variations with the curves of M. gilletii and 

 the hybrid. The curve of M. arnoldiana is the highest 

 throughout, excepting in the polarization reaction, and 

 in many instances it is much higher than the curve of 

 M. gilletii and the hybrid. The curve of M. gilletii is 

 higher than the curve of M. hybrida in the reaction with 

 temperature, chloral hydrate, hydrochloric acid, potas- 

 sium sulphocyanate, potassium sulphide, sodium hydrox- 

 ide, sodium salicylate, uranium nitrate, and strontium 

 nitrate ; and the same or nearly the same in all other reac- 

 tions, excepting with polarization, in which it is lower, 

 the same, or nearly the same. The best reagents in the 

 differentiation of these two starches are chloral hydrate, 

 potassium sulphide, sodium hydroxide, sodium salicylate, 

 uranium nitrate, and strontium nitrate. The very high 

 reactions of M. arnoldiana with'chromic acid, pyrogallic 



