METHODS USED IN THE STUDY OF STARCHES. 



29 



and strontium nitrate; in Richardia, chloral hydrate, 

 chromic acid, hydrochloric acid, sodium hydroxide, and 

 sodium salicylate; in Musa, chloral hydrate, chromic 

 acid, pyrogallic acid, sodium salicylate, and cobalt ni- 

 trate; in Phaius, chloral hydrate, chromic acid, nitric 

 acid, hydrochloric acid, potassium hydroxide, potassium 

 iodide, potassium sulphocyanate, potassium sulphide, so- 

 dium hydroxide, sodium sulphide, and sodium salicylate ; 

 in Miltonia, chloral hydrate, chromic acid, hydrochloric 

 acid, potassium iodide, and sodium salicylate ; in Cym- 

 bidium, chloral hydrate, chromic acid, sodium salicylate, 

 barium chloride, and mercuric chloride; and in Calantlie, 

 chloral hydrate, chromic acid, nitric acid, hydrochloric 

 acid, potassium hydroxide, and sodium salicylate. In- 

 stances here and there will be found where additional 

 reagents, or reagents of concentrations varying from 

 the standards given, were used. The special reasons for 

 the selections in the various cases will be found in 

 Chapter V. 



12. CHARTS OF REACTION-INTENSITIES OF DIFFERENT 



STARCHES. 



It is difficult or impossible to associate the different 

 reaction-intensities of a given starch with different reag- 

 ents or those of different starches with a single reagent 

 when expressed in figures in such a way as to form an 

 accurate or even a reasonably approximate mental picture 

 of their individual and related values; and, moreover, 

 an association of this kind becomes increasingly difficult 

 or absolutely impossible when one attempts to multiply 

 such pictures in a comparison of the reactions of two 

 or more starches with different reagents or of two or 

 more reagents with a given starch. Hence, it has been 

 found necessary to translate these figures into the forms 

 of curves which, as will be seen, give not only strikingly 

 clear presentations of these extremely varied reaction- 

 intensities, but also, as a corollary, permit of the readiest 

 and most, satisfactory comparisons. It was found during 

 the development of the research that it is desirable to 

 exhibit these peculiarities in six kinds of charts as 

 follows : 



A 1 to A 26, showing the reaction-intensities of all or 

 many of the starches with each agent and 

 reagent. 



B 1 to B 42, showing the reaction-intensities of certain 

 starches with certain agents and reagents. 



C 1, showing the reaction-intensities of genera and sub- 

 genera or other generic subdivisions as regards 

 height, eum, and average. 



D 1 to D 691, showing the velocity-reactions of different 

 starches with different reagents. 



E 1 to E 46, showing composite reaction-intensity curves 

 of the starches of parent- and hybrid-stocks 

 with different agents and reagents. 



F 1 to F 14, showing the percentages of macroscopic and 

 microscopic characters of plants, and of the 

 percentages of the reaction-intensities of 

 starches, as regards sameness to one or the 

 other or both parents, intermediateness, and 

 excess and deficit of development. 



Inasmuch as this research is primarily a comparative 

 investigation of the starches of parent- and hybrid- 

 stocks, the curves that represent parents and offspring 

 have, whenever feasible or desirable, been plotted out 

 together in order to render comparisons easy. For 

 various reasons, hereafter stated, all of these charts have 

 been brought together and now compose the las* part of 

 Chapter IV, page 175, et seq. 



In the groups of charts designated A, B, and E, in 

 the polarization, iodine, gentian-violet, and safranin reac- 

 tions the abscissae are in terms of quantitative light and 

 color values based on an arbitrary scale of 105 in divi- 

 sions of twentieths ; in the temperatures of gelatinization 

 in the centigrade scale from 40 to 95 in divisions of 

 2.5 ; and in the gelatinization experiments with different 

 reagents in a duplex scale, the upper portion giving the 

 time of complete or practically complete gelatinization 

 (95 per cent or more of the total starch), and the lower 

 portion the percentage of the total starch gelatinized 

 when complete or practically complete gelatinization has 

 not occurred within 60 minutes. In Charts A 1 to A 26 

 the vertical lines that are projected from the plant names 

 are extended to the abscissas that represent the reaction- 

 intensity values. Thus, if gelatinization is complete or 

 practically complete at the end of 5 minutes the line is 

 carried to the 5-minute abscissa ; if 80 per cent is gela- 

 tinized at the end of the 60-minute period the line is 

 carried to the lower part of the scale that is, to the 

 abscissa designated 80 per cent of the total starch gela- 

 tinized in 60 minutes, and so on. The second form of 

 chart, including B 1 to B 40, while having the same 

 abscissae as the first and fifth forms have different ordi- 

 nates, and Charts B 41 and B 42 while having the same 

 ordinates as the others of this group have wholly or partly 

 different abscissae to meet special conditions. In these 

 charts the reaction-intensity values have been recorded 

 at the proper abscissa on each ordinate and then a line 

 projected from ordinate to ordinate to form a curve. In 

 Charts E 1 to E 46 the ordinates represent the various 

 agents and reagents, the values are recorded as in group 

 B 1 to B 40, and in each chart the curves of the reaction- 

 intensities of parent-stocks and offspring are presented. 

 In Chart C 1 the abscissas are in terms of height, sum, and 

 average reaction-intensities, and the ordinates represent 

 genera, subgenera, or generic subdivisions. In charts 

 D 1 to D 670 there arq given records of the progress of 

 gelatinization in per cent-time, the curves of each set of 

 parent-stocks and offspring being recorded on each chart, 

 excepting in case of a few special charts. The abscissas 

 are in terms of percentages of total starch and the ordi- 

 nates are in time-intervals of 5 minutes. While deter- 

 mining the percentage of total starch gelatinized at defi- 

 nite time-intervals simultaneous records were made at 

 the same periods of the total number of grains com- 

 pletely gelatinized. When these two sets of data are 

 reduced to curves it is found that varying differences 

 are exhibited by the different starches, in the case of 

 each starch with the various reagents, and by the differ- 



