150 



REACTION-INTENSITIES OF STARCHES. 



studied, the maximum and minimum temperatures will 

 be as shown in Chart B 6, in which the temperatures 

 as plotted out by the standard scale are represented by 

 the heavy continuous line, and those by the modified scale 

 by the broken line. It will be seen that the effect of the 

 new scale is not only to accentuate differences, but also 

 to bring about some differences in the relative positions 

 of the curves as regards inversion and reversion. The 

 first noticeable difference of importance is seen in Hip- 

 peastrum, in which in all three starches with the old 

 calibration the temperature curve is the higher, while 

 with the new it is lower in two and higher in one, and 

 with marked differences in the degree of separation of the 

 two curves. In Hwmanthus with the former the tem- 

 perature curve is the higher in both species, while 

 with the latter the two curves are practically alike 

 in the first species and the temperature curve is 

 very much lower in the second species, and so 

 on throughout the chart. It will be seen, however, that 

 the important characteristics pointed out in the preceding 

 charts are present with both forms of calibration — that 

 is, independence in the variations of the two curves dur- 

 ing their progress, with some tendency to concordance, 

 inversions and reversions of the curves at points, and 

 independence of the fluctuations of the curves of each 

 reagent and of the points of inversion, recrossing and 

 separation of the curves in each chart of that which is 

 recorded iu any other chart. The standard calibration 

 adopted for the temperature experiments is preferable to 

 the other because better adapted for future investigations 

 and, therefore, also for comparisons of the results of the 

 present research with those of subsequent studies. 



The peculiarities elicited by these charts are extra- 

 ordinary; they are harmonious in the demonstration of 

 certain fundamental principles ; and they positively indi- 

 cate that they are conditioned by both kind of reagent 

 and kind of starch. It is, consequently, well worth while 

 to extend these studies by means of a group of charts 

 in which a given reagent will be taken as a standard of 

 comparison with each of the other reagents, and in addi- 

 tion to supplement this with another group in which 

 each chart shall present the reactive-intensities of two 

 selected reagents. To this end one group of charts. 

 Charts B' 6 to B 30, inclusive, and another, B 31 to B 42, 

 have been prepared. In the former the nitric-acid reac- 

 tions are taken as the standard of comparison, these 

 reactions being particularly well adapted for the purpose 

 because of their wide range and their exceptional value 

 in the differentiation of genera, subgeneric divisions, 

 species, and hybrids. Much space would be required to 

 go over all the first group of charts individually and in 

 detail, and indeed this is not necessary if the plan 

 adopted in comparing Charts B 1 and B' 6 is pursued. 

 There are, however, several points to which, because of 

 their broad application, especial reference should be 

 made: First, the marked differences exhibited by the 

 various agents and reagents in the range of activities, 

 even when the latter are plotted out upon the same basis 

 of valuation, as in the case of all of the chemical rea- 

 gents; second, the independence of the curve of each 

 agent and reagent of the curve of every other (in several 

 instances, however, as in the anilines and copper salts, 

 there are no important differences) ; third, the wide 



differences in values exhibited by different agents and 

 reagents in the differentiation of genera, subgeneric divi- 

 sions, species, etc. ; fourth, the differentiation of certain 

 genera, subgeneric divisions, and species by one reagent 

 without differentiation by others ; fifth, the differences 

 in the manner of differentiation by different agents and 

 reagents of genera, subgeneric divisions, and species; 

 sixth, the repeated inversions and reversions of the two 

 curves in almost every chart, and the entire independence 

 of the points of crossing in one chart of those in another ; 

 seventh, the marked variations that occur in the degree 

 of separation of the two curves in each chart, and in each 

 chart compared with each other chart; and eighth, the 

 suggestion at least of a tendency to some correspondence, 

 varying in extent, throughout the series of curves in the 

 up and down movements of the curves. Of not less or 

 even of greater interest and value are the second group of 

 charts (Charts B 31 to B 42, inclusive) which present 

 the reaction-intensities of selected pairs of reagents, such 

 as chromic acid and pyrogallic acid, sulphuric acid and 

 hydrochloric acid, nitric acid and sulphuric acid, nitric 

 acid and hydrochloric acid, potassium hydroxide and so- 

 dium hydroxide, potassium sulphide and sodium sid- 

 phide, etc. Probably in no other way can the data of 

 the specificity of each agent and reagent and of each form 

 of starch be more convincingly exhibited. These charts 

 are worthy of careful study. 



The differences shown in the reactions of chromic 

 acid and pyrogallic acid (Chart B 31) are very striking 

 and full of interest, and the chart is worthy of a carefully 

 detailed study. Considered from a rather general aspect, 

 it will be seen that the chromic-acid curve undergoes 

 much less variation than that of pyrogallic acid ; that in 

 some parts of the chart the chromic-acid curve is higher, 

 in other parts lower, and in other parts the same or prac- 

 tically the same as the pyrogallic-acid curve; that the 

 two curves rise and fall for the most part at the same 

 ordinates and at points to indicate generic and subgeneric 

 dividing lines ; that the quantitative differences between 

 the curves vary within wide limits, not only in different 

 genera but also among members of the same genus, 

 especially among subgeneric representatives; and that 

 inversions and reversions of the curves occur at a num- 

 ber of ordinates at which such deviations are consistent 

 with plant differentiation. 



Among the many peculiarities worthy of more than 

 passing notice are the following: In Amaryllis and 

 Brunsvigia chromic acid failed to bring out any differ- 

 entiation at the end of the 30-minute period, at which 

 time there was 99 per cent of the total starch of each 

 gelatinized, although, as shown by our records during 

 the earlier part of the experiments, the former showed 

 distinctly less reactivity than the latter. Pyrogallic acid 

 elicited, from the beginning and throughout the reaction, 

 very definite differentiation; and it showed very much 

 less reactivity than chromic acid with Amaryllis, but the 

 same reactivity with Brunsvigia, 90 per cent of the former 

 being gelatinized in 60 minutes and 98 per cent of the 

 latter, in 30 minutes. The Hippeastrums show dis- 

 tinctly higher reactivities with chromic acid than with 

 pyrogallic acid, and the quantitative differences exhibited 

 by H. titan and E. ossvltan are very markedly larger 

 than those shown by H. dceones. In Hcemanthus the 



