108 



HISTOLOGIC PROPERTIES AND REACTIONS. 



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. 



(3) In /. cengialti, the very high reactions with sul- 

 phuric acid, potassium sulphoeyanate, and sodium sali- 



; the high reactions with polarization, chromic acid, 

 and sodium hydroxide; the moderate reactions with io- 

 dine, gentian violet, safranin, hydrochloric and, potas- 

 sium hydroxide, and potassium iodide; the low reactions 

 with temperature, chloral hydrate, pyrogallic acid, nitric 

 aeid, sodium sulphide, strontium nitrate, copper nitrate, 

 and cupric chloride; and the very low reactions with 

 potassium sulphide, uranium nitrate, cobalt nitrate, 

 barium chloride, and mercuric chloride. 



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

 phuric acid, potassium sulphoeyanate, and sodium 

 salicylate; the high reactions with chromic acid and so- 

 dium hydroxide; the moderate reactions with polariza- 

 tion, iodine, gentian violet, safranin, temperature, pyro- 

 gallic acid, nitric acid, hydrochloric acid, potassium 

 hydroxide, and potassium iodide; the low reactions with 

 chloral hydrate, sodium sulphide, calcium nitrate, stron- 

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

 very low reactions with potassium sulphide, uranium 

 nitrate, cobalt nitrate, barium chloride, and mercuric 

 chloride. 



Following is a summary of the reaction-intensities: 



32. COMPARISONS OF THE StaECIIES OF IlilS CEX- 

 O TAT. TT, I. PALLIDA QUEEN OF MAY, AND I. MRS. 

 ALAN GREY. 



In histologic characteristics, polariscopic figures, reac- 

 tions with selenite and iodine, and with various chemi- 

 cal reagents the starches of the parents and hybrid ex- 

 hibit properties in common in varying degrees of de- 

 velopment, the sum of which in each case is characteristic 

 of the starch. Lnasmuch as one of the parents is prob- 

 ably merely a dwarf form of the other, but little difference 

 is to be expected between either parents or parents and 

 hybrid. The starch of /. cengialti in comparison with 

 that of I. pallida queen of may contains fewer compound 

 grains and aggregates; the grains arc less irregular, more 

 rounded, but do1 so slender. The hilum when not fis- 

 sured is more distinct; more often, more deeply and more 

 extensively fissured; and the eccentricity is greater. 

 The lamellae are usually not so distinct, coarser, and ex- 

 hibit a notch corresponding to a notch in the distal 

 margin that was not noted in I. pallida queen of may. 

 The size of the grains is somewhat larger. In the polari- 

 scopic, selenite, and qualitative iodine reactions many 

 differences are recorded. In the qualitative reactions 

 with chloral hydrate, hydrochloric acid, potassium iodide, 

 sodium hydroxide, and sodium salicylate various differ- 

 ences arc noted, some of them quite individual and dis- 

 tinctive. The starch of the hybrid in comparison with 

 the starches of the parents contains compound grains and 

 aggregates in about the same numbers and of the same 

 types as in /. pallida queen of may; the grains are more 

 regular than in either parent. In certain respects the 



form is closer to that of /. cengialti, but in most features 

 closer to that of the other parent. The hilum is in 

 character closer to /. pallida queen of may, but the 

 eccentricity is greater than in either parent, yet closer 

 to this parent. The lamellae are Less distinct than in 

 either parent, but they are in their general characters 

 closer on the whole to /. cengialti. The size is less than 

 in cither parent, but closer to 1 . pallida quei n of may. 

 The polariscopic and selenite reactions are closer to 

 those of 1. pallida queen of may, but the qualitative 

 iodine reactions are closer to those of the other parent. 

 In the qualitative reactions with the chemical reagents 

 the hybrid is very much more closely related to I. pallida 

 queen of may. 



Ueactionintensities Expressed by Light, Color, and Tempera- 

 ture Reactions. 

 Polarization: 



I. cengialti, moderately high to high, value 60. 



I. pallida queen of may, low to high, lower than in I. cengialti, 



value 50. 

 I. mra. alan grey, low to high, lower than in either parent, value 45. 

 Iodine: 



I. cengialti, moderate, value 45. 



I. pallida queen of may, moderate, less than in I. cengialti, value 35. 

 I. mra. alan grey, moderate, deeper than in either parent, value 50. 

 Gentian violet: 



I. cengialti, moderate, value 45. 



I. pallida queen of may, moderate, Blightly deeper than in I. cen- 

 gialti, value 48. 

 I. mrs. alan grey, light to moderate, less than in either parent, 

 value 40. 

 Safranin: 



I. cengialti, moderate, value 50. 



I. pallida queen of may, moderate, slightly deeper than in I. cen- 

 gialti, value 52. 

 I. mrs. alan grey, moderate, less than in either parent, value 45. 

 Temperature: 



I. cengialti, in the majority at 70 to 72°, in all at 74 to 76°, mean 75°. 

 I. pallida queen of may, in the majority at 71 to 73°, in all at 75 



to 75.8°, mean 75.4°. 

 I. mra. alan grey, in the majority at 69 to 70°, in all at 73 to 74.5°, 

 mean 73.75°. 



The reactivity of I. cengialti is higher than that of 

 the other parent in the reactions with polarization, 

 iodine, and temperature; and lower with gentian violet 

 and safranin. With the exception of the first two the 

 differences are small, and in the case of temperature 

 probably within the limits of error. The reactivity of 

 the hybrid is the lowest of the three in the polarization, 

 gentian-violet, safranin, and temperature reactions, and 

 the highest of the three in the iodine reactions. The 

 hybrid is closer to /. cengialti than to that of the other 

 parent in the iodine, gentian-violet, safranin, and temp- 

 erature reactions, but the reverse in polarization reactions. 



Table A 32 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 cuTves of 

 the starches of Iris cengialti, I. pallida queen of may, 

 and I. mrs. alan grey. showing the quantitative differences 

 in the behavior toward different reagents at definite time- 

 intervals. (Charts D 421 to D 44L) 



The most conspicuous features of this group of charts 

 are: 



(1) The closeness of all three curves, with the ex- 

 ception of the chloral-hydrate reaction, in which the 

 curves markedly diverge after the first. 5 minutes. Ex- 

 cepting the reactions with nitric acid, sulphuric acid, 

 potassium sulphide, cobalt nitrate, and barium chloride, 

 there is sufficient separation of the curves, one or more, 

 to permit of more or less satisfactory differentiation. 

 It is of particular interest to note that the parental 

 curves tend to a more marked closeness than does the 



