IRIS. 



105 



hybrid and /. trojana curves are practically absolutely 

 the same and above the I. iberica curve in the reactions 

 with sodium salicylate ; almost identical with the parental 

 curves in the reaction with potassium sulphocyanate ; at 

 first intermediate and then the highest of the three in the 

 reactions with sodium hydroxide, although there are but 

 little difEerences ; and the highest and then intermediate in 

 the reactions with potassium iodide, tending to be close to 

 the curve of /. trojana. The hybrid curve is lower than the 

 parental curves in the reactions with potassium hydrox- 

 ide, cupric chloride, cobalt nitrate, barium chloride, and 

 mercuric chloride, although the cobalt-nitrate and 

 barium-chloride curves are very little different from the 

 parental curves; and the highest throughout the 60 

 minutes in the uranium-nitrate reaction. 



(4) In very few reactions is there a marked period 

 of early resistance followed by a comparatively rapid 

 gelatinization. A brief period of early resistance of aU 

 three starches is suggested by the curves of the strontium- 

 nitrate reaction, and of one or the other parent or the 

 hybrid in the reactions with chloral hydrate, chromic 

 acid, calcium nitrate, uranium nitrate, and copper ni- 

 trate, especially in the last. 



(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 the reac- 

 tions with pyrogallic acid, sulphuric acid, hydrochloric 

 acid, potassium iodide, potassium sulphocyanate, sodium 

 hydroxide, sodium salicylate, uranium nitrate, and cop- 

 per nitrate ; at 15 minutes with chromic acid, potassium 

 hydroxide, calcium nitrate, strontium nitrate, and cupric 

 chloride ; at the end of 30 minutes with chloral hydrate, 

 nitric acid, potassium sulphide, and sodium sulphide; 

 and at the end of 60 minutes with cobalt nitrate, barium 

 chloride, and mercuric chloride (with the last perhaps 

 at the end of 30 to 45 minutes) . 



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 30 and 

 Charts D 379 to D 399.) 



The reactivities of the hybrid are the same as those 

 of the seed parent in the iodine, gentian violet, and 

 safranin reactions ; the same as those of the pollen parent 

 with potassiimi iodide and sodium hydroxide; the same 

 as those of both parents with potassium sulphocyanate 

 and sodium hydroxide ; intermediate with temperature, 

 chloral hydrate, chromic acid, pyrogallic acid, nitric acid, 

 sulphuric acid, hydrochloric acid, potassium sulphide, 

 sodium sulphide, calcium nitrate, strontium nitrate, and 

 copper nitrate (in four being closer to the seed parent, 

 in two being closer to the pollen parent, and in six being 

 mid-intermediate) ; the highest with uranium nitrate, 

 and nearer that of the pollen parent; and the lowest with 

 polarization, potassium hydroxide, cobalt nitrate, cupric 

 chloride, barium chloride, and mercuric chloride (in 

 three being closer to the seed parent, in one closer to the 

 pollen parent, and in two being as close to one as to 

 the other parent). 



The following is a summary of reaction-intensities: 

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

 as both parents, 2 ; intermediate, 12 ; highest, 1 ; lowest, 6. 



It seems from the foregoing data that the seed parent 

 has exercised much more influence than the pollen parent 

 on the characters of the starch of the hybrid. Apart 

 from this the most conspicuous features are the marked 

 tendency to intermediateness and a tendency to lowness 

 of the hybrid. 



Composite Cdeves of Eeaction-intensities. 



This section treats of the composite curves of the 

 reaction-intensities, showing the differentiation of the 

 starches of Iris iberica, I. trojana, and /. ismali. (Chart 

 E 30.) 



The most conspicuous features of this chart are: 



(1) The closeness of all three curves, the parental 

 curves running so closely together as to suggest very 

 closely related' species (/. iberica is, however, relegated 

 to Oncocylus and /. trojana, to Apagon, well-separated 

 subgenera of the rhizomatous series). (The groupings 

 of the Irids by different botanists are by no means the 

 same, and it is recognized as being questionable if 

 the classification of the entire genus must not be 

 reconstructed.) 



(2) The curve of /. iberica tends, with the exception 

 of the polarization and temperature reactions, to be below 

 that of /. trojana; but the differences are usually slight, 

 and most marked in those with iodine, gentian violet, 

 temperature, chloral hydrate, chromic acid, potassium 

 sulphocyanate, sodium sulphide, sodium salicylate, cal- 

 cium nitrate, uranium nitrate, copper nitrate, cupric 

 chloride, and mercuric chloride. 



(3) The curve of the hybrid wavers in its parental 

 relationships, sometimes being closer to one parent and 

 at others to the other, with for the most part a tendency 

 to sameness or intermediateness, occasionally above or 

 below parental extremes. 



(4) 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 

 hydroxide; the moderate reactions with polarization, 

 iodine, gentian violet, safranin, temperature, pyrogallic 

 acid, and potassium hydroxide; the low reactions with 

 chloral hydrate, nitric acid, hydrochloric acid, sodium 

 sulphide, calcium nitrate, strontium nitrate, copper ni- 

 trate, and cupric chloride; and the very low reactions 

 with potassium sulphide, uranium nitrate, cobalt nitrate, 

 barium chloride, and mercuric chloride. 



(5) In 7. trojana, the very high reactions with sul- 

 phuric acid, potassium sulphocyanate, and sodium sali- 

 cylate ; the high reactions with chromic acid and sodium 

 hydroxide ; the moderate reactions with polarization, io- 

 dine, gentian violet, safranin, chloral hydrate, pyrogallic 

 acid, nitric acid, hydrochloric acid, potassium hydroxide, 

 and potassium iodide ; the low reactions with temperature, 

 sodium sulphide, calcium nitrate, strontium nitrate, cop- 

 per nitrate, and cupric chloride; and the very low reac- 

 tions with potassium sulphide, uranium nitrate, cobalt 

 nitrate, barium chloride, and mercuric chloride. 



(6) In the hybrid, the very high reactions with sul- 

 phuric acid, potassium sulphocyanate, and sodium salicyl- 

 ate; the high reactions with chromic acid and sodium 

 hydroxide ; the moderate reactions with polarization, io- 

 dine, gentian violet, chloral hydrate, pyrogallic acid, 

 nitric acid, potassium hydroxide, and potassium iodide; 

 the low reactions with temperature, hydrochloric acid, 

 sodium sulphide, calcium nitrate, uranium nitrate, stron- 

 tium nitrate, copper nitrate, and cupric chloride ; and the 

 very low reactions with potassium, sulphide, cobalt nitrate, 

 barium chloride, and mercuric chloride. 



Tollowing is a summary of the reaction-intensities : 



