\ 



126 



HISTOLOGIC PROPERTIES AND REACTIONS. 



such differences as are recorded probably fall within the 

 limits of error of experiment ; in those with chromic acid 

 and pyrogallic acid the differences are insignificant; and 

 in those with nitric acid, hydrochloric acid, and potas- 

 sium hydroxide the differences are not marked, yet suf- 

 ficient for definite differential purposes. In the latter 

 reactions it will be observed that the relations of the 

 curves of the three starches differ in each in the nitric- 

 acid reaction the starch of R. albo-maculata is the most 

 reactive, R. elliottiana the least, and the hybrid inter- 

 mediate; in the hydrochloric-acid reaction the order of 

 reactivity is R. albo-maculata, R. elliottiana, and hybrid ; 

 and in the potassium-hydroxide reaction the order is 

 hybrid, R. elliottiana, and R. albo-maculata. The great- 

 est interest centers perhaps in the differences in reac- 

 tivity toward the different reagents, there being repre- 

 sented in the eight charts almost the extremes of reac- 

 tivities. In the chloral-hydrate, sulphuric-acid, and 

 sodium-salicylate reactions within 5 minutes all three 

 starches are gelatinized; with pyrogallic acid there is 

 very little effect even at the end of 60 minutes; while 

 with chromic acid, nitric acid, hydrochloric acid, and 

 potassium hydroxide there are in-between gradations. 

 It is also of interest to note the different courses of the 

 curves with these four 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 40 and 

 Charts D 545 to D 552.) 



The reactivities of the hybrid are the same as those 

 of the seed parent in the iodine reaction; the same as 

 those of the pollen parent in none; the same as those 

 of both parents in the reactions with chromic acid, pyro- 

 gallic acid, sulphuric acid, and sodium salicylate ; inter- 

 mediate in the polarization, temperature, and nitric acid 

 reactions, in all being mid-intermediate; highest with 

 gentian violet, safranin, chloral hydrate, and potassium 

 hydroxide; and the lowest with hydrochloric acid, it 

 being closer to that of the pollen parent. 



The following is a summary of the reaction-intensi- 

 ties: Same as seed parent, 1; same as pollen parent, 0; 

 same as both parents, 4; intermediate, 3; highest, 4; 

 lowest, 1. 



It is interesting to note that while in one reaction 

 there is sameness in relation to the seed parent, there 

 is not in any reaction sameness to the pollen parent, 

 although in 5 reactions out of the 13 the inclination is 

 to the pollen parent and in only the one referred to is 

 it to the seed parent. Tendencies to mid-intermediate- 

 ness, to highest reactivity, and to sameness as both 

 parents are quite apparent. 



COMPOSITE CURVES OF THE REACTION-INTENSITIES. 



This section treats of the composite curves of the 

 reaction-intensities, showing the differentiation of the 

 starches of Richardia albo-maculata, R. elliottiana, and 

 R. mrs. roosevelt. (Chart E 40.) 



The most conspicuous features of this chart are: 



Marked closeness, almost identity, of all three curves. 



In fact, such differences as are shown are usually so 



small as to fall within the limits of error of record. It 



would perhaps be hazardous to reach a definite diagnosis 



of one from the other by these curves, yet if taken in 

 connection with the curves showing the reaction-intensi- 

 ties at definite time-intervals differentiation appears to 

 be satisfactory. From these curves one might naturally 

 be led to the belief that we are dealing with varieties 

 of a species and not with two recognized species (even 

 though they might belong to a species subgroup) and 

 a hybrid. From these investigations (which are incon- 

 clusive) the parents should be regarded as varieties of a 

 given species. It is of interest to compare these curves 

 with those of the hippeastrums, the parents of which 

 are garden varieties that have come from closely related 

 parentage. The marked excursions of the curves, show- 

 ing wide variations in the reactive intensities with the 

 different reagents, are very striking. 



41. COMPARISONS OF THE STARCHES OF MUSA 

 AKNOLDIANA, M. GILLETII, AND M. HYBRIDA. 



In the histologic characteristics, polariscopic figures, 

 reactions with selenite, reactions with iodine, and quali- 

 tative reactions with the various chemical reagents the 

 starches of the parents have properties in common in 

 varying degrees of development and also certain individ- 

 ualities, and the starch of the hybrid has properties like 

 those of one or the other or both parents, and also certain 

 individualities ; but it is, on the whole, distinctly closer 

 to Musa gilletii than to the other parent. The starch 

 of M. qilletii in comparison with that of M. arnoldiana 

 has only one of the two types seen in M. arnoldiana, but 

 there are aggregates that are not found in the latter; 

 and there are more numerous elongated forms. The 

 hilum is somewhat more often fissured, and eccentricity 

 is somewhat less in some of the forms. The lamellae are 

 more often distinct, not so fine, and less numerous. The 

 size is slightly larger. In the polariscopic, selenite, and 

 qualitative iodine reactions there are many differences 

 which seem to be of a minor character. In the qualita- 

 tive reactions with chloral hydrate, chromic acid, pyro- 

 gallic acid, sodium salicylate, and cobalt nitrate there 

 are very many differences, many of which quite definitely 

 individualize one or the other parent. The starch of the 

 hybrid in comparison with the starches of the parents 

 shows in almost every feature a closer relationship to the 

 starch of the pollen parent. It contains the two types of 

 compound grains found in M. arnoldiana and the aggre- 

 gates of the other parent, and there is a type of compound 

 grain that is peculiar to the hybrid. The hilum is more 

 frequently fissured than in either parent. The lamellne 

 are in character and arrangement more like those of 

 M. gilletii, but in number closer to M. arnoldiana. In 

 size some of the grains exceed those of the parents. In 

 the polariscopic, selenite, and qualitative iodine reactions 

 there are many differences, but the inclinations of the 

 hybrid are distinctly to M. gilletii. In the qualitative 

 chemical reactions the leanings are very definitely to one 

 or the other or both parents, with, on the whole, a dis- 

 tinctly closer relationship to M . gilletii, the pollen parent. 



Reaction-intensities Expressed 1>y Light, Color, and Tempera- 

 ture Reactions. 

 Polarization : 



M. arnoldiana, low to high, value 40. 



M. gilletii, low to high, higher than in M. arnoldiana, value 45. 



M. hybrida, low to high, higher than in either parent, value 50. 



