IRIS. 



107 



same as that of the other parent in the saf ranin reaction ; 

 and the highest of the three in the temperature reaction. 

 The hybrid is nearer /. iberica than to /. cengialti in the 

 polarization, iodine, and temperature reactions, but 

 nearer the other parent in the gentian violet and saf ranin 

 reactions. 



Table A 31 shows the reaction-intensities in percent- 

 ages of total starch gelatinized at definite intervals 

 (minutes). 



Velocity-reaction Cdkves. 



This section treats of the velocity-reaction curves of 

 the starches of Iris iberica, I. cengialti, and /. dorah, 

 showing the quantitative differences in the behavior 

 toward different reagents at definite time-intervals. 

 (Charts D 400 to D 420.) 



The most conspicuous features of this group of curves 

 are: 



(1) The closeness of all three curves, occasionally 

 almost identical, indicating corresponding relationships 

 of the parents and little modification of parental pecu- 

 liarities in the hybrid. The hybrid curve relative to the 

 parental curves shows marked variability in so far as it 

 sometimes follows one or the other parent closely, or is 

 the highest or the lowest or tends to intermediateness, 

 as the case may be. The hybrid curve inclines to differ 

 as much from the parental curves as the latter do from 

 each other. The tendency to separation of the parental 

 curves is more marked in this group than in the previous 

 group, and vdth the exception of the reactions with sul- 

 phuric acid, potassium sulphocyanate, potassium sul- 

 phide, sodium hydroxide, sodium salicylate, strontium 

 nitrate, cobalt nitrate, copper nitrate, and barium chlo- 

 ride there is more or less marked separation, with a 

 tendency generally for two of the three curves to keep 

 close, sometimes the two parental curves and at others 

 one parental curve with the hybrid curve. In some of 

 the reactions noted there is definite although unimportant 

 separation, as in those with sodium salicylate, strontium 

 nitrate, copper nitrate, and barium chloride. 



(2) The sameness or marked closeness of the pa- 

 rental curves in the reactions with chloral hydrate and 

 chromic acid; the sameness or marked closeness of all 

 three curves with sulphuric acid, potassium sulphocya- 

 nate, potassium sulphide, sodium hydroxide, sodium sali- 

 cylate, strontium nitrate, cobalt nitrate, and copper 

 nitrate ; the sameness or marked closeness of the hybrid 

 curve with one or the other parental curve with pyro- 

 gallic acid, nitric acid, hydrochloric acid, calcium ni- 

 trate, and mercuric chloride. 



(3) The varying positions of the hybrid curves in 

 relation to the parental curves in the different reactions, 

 and the marked tendency for the hybrid curves to be 

 higher or lower than the parental curves with almost not 

 the least tendency to intermediateness. 



(4) In a few instances there is evidence of a com- 

 paratively marked early resistance of one or two or all 

 three starches, as the case may be, as in I. iberica in the 

 chloral-hydrate and I. iberica and I. cengialti in the 

 chromic-acid reactions ; in 1. cengialti in those with pyro- 

 gallic acid, nitric acid, sodium sulphide, copper nitrate, 

 and cupric chloride. This peculiarity, in so far as the 

 parents are concerned, is therefore almost confined to 

 /. cengialti, and it is not observed in the hybrid unless 

 perhaps in the uranium nitrate reaction. 



(5) The earliest period during the 60 minutes at 

 which the three curves are best separated to differentiate 

 the starches varies with the different reagents. Approxi- 

 mately, this period occurs within 5 minutes in most of 

 the reactions, including the reactions with pyrogallic 

 acid, nitric acid, sulphuric acid, potassium hydroxide. 



potassium sulphocyanate, sodium hydroxide, sodium sul- 

 phide, sodium salicylate, calcium nitrate, uranium ni- 

 trate, and copper nitrate ; at the end of 15 minutes with 

 chloral hydrate, chromic acid, hydrochloric acid, potas- 

 sium iodide, strontium nitrate, and cupric chloride; 

 and at the end of 60 minutes with potassium sulphide, 

 cobalt nitrate, barium chloride, and mercuric chloride. 

 In some of these cases there is little or no practical dif- 

 ferentiation at these respective periods. 



Eeaction-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 31 and 

 Charts D 400 to D430.) 



The reactivities of the hybrid are the same as those 

 of the seed parent in the reactions with polarization, 

 iodine, sodium hydroxide, barium chloride, and mercuric 

 chloride ; the same as those of the pollen parent in those 

 with saf ranin, hydrochloric acid, and potassium sulphide ; 

 the same as those of both parents in the cobalt-nitrate 

 reaction ; intermediate in that with calcium nitrate, and 

 closer to the seed parent; highest in those with gentian 

 violet, temperature, chromic acid, pyrogallic acid, nitric 

 acid, sulphuric acid, potassium iodide, sodium sulphide, 

 uranium nitrate, strontium nitrate, copper nitrate, and 

 cupric chloride (in six being closer to the seed parent, 

 in five closer to the pollen parent, and in one as close 

 to one a^ to the other parent) ; and lowest with chloral 

 hydrate, potassium hydroxide, potassium sulphocyanate, 

 and sodium salicylate (in one being closer to the seed 

 parent, in two closer to the pollen parent, and in one as 

 close to one as to the other parent) . 



The following is a summary of the reaction-intensi- 

 ties : Same as seed parent, 5 ; same as pollen parent, 3 ; 

 same as both parents, 2; intermediate, 1; highest, 11; 

 lowest, 4. 



The seed parent has apparently influenced to a more 

 marked extent than the pollen parent the properties of 

 the starch of the hybrid. The sameness to the seed 

 parent coupled with the tendency to closeness to the seed 

 par.ent in the reactions in which the hybrid is in excess 

 of the parents is quite marked. The tendency to the 

 highest or lowest reactivity of the hybrid is quite conspic- 

 uous, this being noted in more than half of the reactions. 



Composite Curves of Reaction-intensities. 



This section treats of the composite curves of the 

 reaction-intensities, showing the differentiation of the 

 starches of 7m iberica, I. cengialti, and I. dorak. (Chart 

 £ 31.) 



The most conspicuous features of this chart are : 



(1) The marked closeness of all three curves through- 

 out, there being no tendency in any reaction for a marked 

 departure of any one curve from the other two. The 

 curves are so close as to suggest either very closely re- 

 lated species or mere varieties, the latter rather than the 

 former. The species are, however, classed in different 

 subgenera: I. iberica in Oncocyclus, and I. cengialti in 

 Pogoniris and Regelia. I. cengialti is regarded as being 

 probably a dwarf variety of I. pallida, which it closely 

 resembles. For the most part the differences in the curves 

 fall within or close to the limits of error of experiment, 

 so that little or nothing of importance can be gained 

 from a critical comparison. At some points one parental 

 curve is higher than the other; and the hybrid curve 

 courses vdth one or the other or both parental curves, 

 here and there running above or below both. 



(2) In I. iberica, the very high reactions with sul- 

 phuric acid, potassium sulphocyanate, and sodium sali- 

 cylate; the high reactions with chromic acid and sodium 



