104 



HISTOLOGIC PROPERTIES AND REACTIONS. 



Saf ranin : 



I. iberica, moderate, value 45. 



I. trojana, moderate, deeper than in I. iberica, value 50. 



I. ismali, moderate, the same as in I. iberica, value 45. 

 Temperature : 



I. iberica, in the majority at 69 to 70, in all at 71 to 72.5, mean 

 71.75. 



I. trojana, in the majority at 70 to 71.5, in all at 73.2 to 75, 

 mean 72.1. 



I. ismali, in the majority at 69 to 71. in all at 72 to 74, mean 73. 



The reactivity of /. iberica is higher than that of the 

 other parent in the polarization and temperature experi- 

 ments, and lower in iodine, gentian-violet, and safraiiiu 

 reactions. The reactivity of the hybrid is the same or 

 practically the same as that of /. iberica in the iodine, 

 gentian-violet, and safranin reactions; the lowest of the 

 three in the polarization reaction; and intermediate be- 

 tween those of the parents in the temperature reaction. 

 The hybrid is nearer to /. iberica in the iodine, gentian- 

 violet, and safranin reactions, nearer to the other parent 

 in the polarization reactions, and intermediate in the 

 temperature reaction. 



Table A 30 shows the reaction-intensities in percent- 

 ages of total starch gelatinized at definite intervals 

 (minutes). 



VELOCITY-REACTION CURVES. 



This section treats of the velocity-reaction curves of 

 the starches of Iris iberica, I. trojana, and /. ismali, show- 

 ing the quantitative differences in the behavior toward 

 different reagents at definite time-intervals. (Charts 

 D 379 to D 399.) 



The most conspicuous features of this group of curves 

 are: 



(1) The closeness of all three curves, indicating not 

 only a corresponding relationship of the parents, but 

 also very little modification of parental peculiarities 

 in the hybrid. As regards the latter, the tendency of 

 the curve is to follow closely that of one or the other 

 parent or be of some degree of intermediateness. The 

 only instances where there seems to be a notable inclina- 

 tion for separation of the curves are in the reactions with 

 chloral hydrate, hydrochloric acid, sodium sulphide, cal- 

 cium nitrate, and mercuric chloride; and with the ex- 

 ception of the last the hybrid curve is between the 

 parental curves and distinctly closer to the curve of one 

 or the other parent. 



(2) The lower reactivity of I. iberica in comparison 

 with the other parent with all of the chemical reagents 

 (excepting in the very rapid sulphuric-acid and the very 

 slow cobalt^nitrate and barium-chloride reactions, where 

 the parental curves are practically absolutely the same), 

 the absence of differentiation doubtless being due to the 

 extreme slowness of gelatinization. 



(3) The variable position of the hybrid curve in 

 relation to the parental curves in the various reactions, 

 with a very definite tendency to iutermediateness or low- 

 ness. In some of the reactions one of the three starches 

 may at first be comparatively slow in reacting, followed 

 by a comparatively rapid reaction, so that the relations 

 of the curves are changed. This is seen in the pyrogallic- 

 acid, strontium-nitrate, and copper-nitrate reactions, in 

 which the hybrid curve is the lowest at the end of 5 min- 

 utes and subsequently intermediate; in the calcium- 

 nitrate reactions, where the curve of /. trojana is the low- 

 est at 5 minutes and then the highest and well separated 

 from the other curves ; and in uranium-nitrate reaction 

 where the parental curves change their relative positions 

 after 5 minutes. The sulphuric-acid chart shows nodiffer- 

 entiation, but the figures at the end of 2 minutes indicate 

 the order of reactivity as follows: I. trojana, I. ismali, 

 and I. iberica, making the hybrid intermediate. The 



TABLE A 30. 



