L66 



REACTION-INTENSITIES OF STARCHES. 



ferent genera, the reaction being in some instances 

 higher, or lower, or the same, or about the same, as the 

 itensity. In comparing the data of 

 di tie rent genera, species, or hybrids, it was usually found 

 I to fall and rise together — in other 

 . that if in one Bet the avera r ,e mean ti mperature 

 of gelatinization an reaction-intensity is at 



en standard and if in the next Bet the temperature 

 reaction-intensity will be higher, 

 although the quanl i relationship between the two 



.an',; but one may rise and the other fall, and so 

 on. The varying relationships of these two sets of reac- 

 tions will be seen by comparing the records in Table B 2 

 and Chart J! 42. Strictly equivalent values in the two 

 not given because the scales are different and 

 arbitrary. The range of temperature reactions arc in- 

 cluded between 51.5° (Lilium parryi) and 83.2">° 

 (Hcemanthus konig albert), representing a range of only 

 about tlin e, while in the reaction-inten- 



, as a whole, the entire scale is included; hence, it 

 follows that strictly comparative values of the excursions 

 of the temperature curve should be amplified two-fifths. 

 This fault, however, does not interfere with the gross 

 comparisons sought. Taking the two averages for the 

 Amaryllis-brunsvigia-brunsdonna group as a starting- 

 point, it will l>c observed that there is a well-marked sepa- 

 ration of the two curves and that the temperature curve 

 is the lower. Both curves fall in Hippeastrum, the tem- 

 perature curve less than the other, and there is an inver- 

 sion of the positions of the two curves, the temperature 

 curve now being the higher. In Hcemanthus both curves 

 are still lower, both being close in the first set but well 

 ated and again reversed in the second set, the tem- 

 ture curve now being the lower as in Amaryllis- 

 brunsvigia-brunsdonna. This last crossing is due to pe- 

 culiarities, several times referred to, of Hcemanthus 

 eus. In Crinum both curves rise and undergo a 

 marked separation in the last set, the temperature curve 

 remaining in all three sets lower and changed to a less 

 degree than the other curve. In Nerine both curves fall 

 and approximate. In Narcissus the reaction-intensity 

 curve remains at the same level as in the last set of 

 Nerine, but the temperature curve rises to a point slightly 

 inti Qsity curve. In all of the follow- 

 the temperature curve falls below 

 the oi . the degree being very variable, and the 



of variability far in excess of what can be account) d 

 ■•: error of calibration above referred to. 



These avert difference -I > no! begin to bring out 



■ ieni and kind of these variation ■ 

 Pound when the data foi members of differenl 

 are compared. For instance, in Amaryllis-bruns- 

 the temperatures of gelatinization are 

 i ne. i he maximum differei ce eing onlv 

 intensities vary between 7G and 

 52, the temperatures for Imaryllis and Brunsdonna i 

 being pi olutely the - me, while the 



i ". ■■ pectivel? 



In other word -. there maj be no dif- 

 ferei. i perature of gelatinization, but a wide 

 difference in reacti ties. I- the Crinum longi- 

 folium-moorei-pow( i the lowest tem- 

 perature of : tion, but the highest average 

 ion intensity. In Iris, in the first three a t the 



ratures are uniformly higher than in the fourth 

 set, but the relative reaction-intensities are the opposite, 

 they being very much lower in the first tl than 



in the last set, and the difference is proportionately far 

 mon marked than in the temperatures of gelatinization. 

 In Begonia, in 11. socotrana the temperature of gela- 

 tinization is very much higher than in the other members 

 of the genus represented, but the reaction-intensity is 

 very decidedly lower. On the other hand, in Hippeas- 

 trum the temperatures of gelatinization and average 

 reaction-intensities are in both cases very closely alike. 

 In Hcemanthus katherina the temperature of gelatiniza- 

 tion is distinctly higher than in II. magnificus, but with 

 the average reaction-intensity, although there is a fa nd- 

 ency, on the whole, for a starch that has a high tem- 

 perature of gelatinization to have a corresponding 

 reaction-intensity. 



In comparing the data of this table it is worthy 

 of note that while there may be evidence in some reaction 

 of a grouping of genera and of subgeneric divisions 

 there may not be in others. For instance, the tempera- 

 ture of gelatinization of the members of two genera may 

 be close, as in the case of Hippeastrum ami Nerine, but 

 the sum and average reaction-intensities may be dis- 

 tinctly different; or the temperatures may more or less 

 distinctly individualize the genu-, as in the case of 

 Lilium; or they may individualize subgeneric groups, 

 as in Iris, in which the first three sets and the last set 

 stand distinctly apart from each other. While it may 

 not be possible positively to recognize a genus upon the 

 basis of temperature of gelatinization and average reac- 

 tion-intensitiy, it is at least possible to state that it may 

 be this or that genus or positively that it can not be a 

 certain genus. For instance, having the data for Hip- 

 peastrum and Nerine, it could perhaps not be stated 

 conclusively which is which, although there is evident 

 differentiation ; but neither could possibly be confounded 

 with Amaryllis-brunsvigia, Lilium. Iris, Musa, Phaius, 

 Miltonia, or Cymhidium ; nor could Lilium be mistaken 

 for Iris or for any other genus with the exception, 

 possibly, of Cymhidium. Lilium and Cymhidium are 

 very widely separated genera, one belonging to Liliaceffi 

 and the other to Orchidaceas, and there should be a wide 

 difference in the sum-total of their reactivities, but the 

 reason why they are not here so differentiated is owing 

 to their great sensitivity to the chemical reagents. So 

 far as the temperature of gelatinization is concerned, it is 

 well established that starches obtained from very remote 

 plant sources may have the same temperature of gela- 

 tinization, which peculiarity applies also to every rea- 

 •;vnf, both of which being in accord with what is to be 

 expected of stereoisomers. On the other hand, they may 

 exhibit differences, which vary in degree with different 

 reagents. Hence, it follows that the starches are to be 

 distinguished from each other by the collective pecu- 

 liarities of each starch compared with those of other 

 starches. 



2. Velocity-reactions with Different 

 Reagents. 



I barta I) 1 to D 601.) 

 Tn the preceding section it was shown, among various 

 conspicuous phenomena, that dim ' hes exhibit a 



wide ransre of reaction-intensities with a criven agent or 



