NOTES AND CONCLUSIONS. 



373 



and qualitative gelatinization reactions with a variety 

 of chemical reagents which represent a wide range of 

 differences in molecular composition. In some instances 

 the stanh molecules alone or largely determine the 

 reaction, while in others both starch and reagent play 

 important parts, as in chemical reactions generally. 

 Tims, in the crystallographic studies of the hemo 

 globin crystals and in the polarization reactions with 

 starch the molecules undergo do change; hence the 

 reactions express peculiarities thai are inherenl to the 

 molecules. In other starch reactions, in the gentian- 

 violet and safranin reactions, the organization of the 

 molecules is either unaffected or affected to an unde- 

 ible degree, the reactions being presumably ad orp- 

 tion phenomena; in the iodine reactions there is prob- 

 ably a feeble chemical combination of the iodine and 

 Btarch, hut without apparent intermolecular disorgan- 

 ization; in the temperature and chemical-reagent reac- 

 tions there is an intermolecular breaking down by a 

 process hi' hydration, with which process there may he 

 iated n actions thai vary in character and number in 

 dance with peculiarities in the composition of the 

 nts. if the molecules of the starches from different 

 Bources are in the form of stereoisomers, it follows, as a 

 corollary, that they must exhibit differences in their 

 behavior with different agents and reagents, and show 

 differences that are related to variation in the kind of 

 agent and in the composition and concentration of the 

 nts. In other words, the reaction in each case is 

 conditioned by the kind of starch and the kin! of 

 agent or reagent. 



Reliability of Methods as Shown uv Charts and 

 Conformity of Results Collectively. 

 It is obvious that tests of the reliability of the 

 methods employed in the differentiation of starches 

 from various sources are to be found in the agreement 

 of the results of repeated experiments and in the <■ m- 

 formity of the results with established data of the syste- 

 matise A- stated in preceding paragraphs, the polari- 

 zation, iodine, and aniline methods arc. notwithstanding 

 their crudity and limitations, reliable if the experiments 

 are carried out with sufficient care; the temperature of 

 gelatinization method is accurate within very narrow 



limits of error; and the gelatinization method u I in 



the present research by mean- of chemical reagents i 

 practically exact. The first three methods arc owing 

 to their usually very restricted range of value-, of very 

 much more usefulness in the differentiation of members 

 of a genus than of different genera, and this applies, 

 although t<» a less decree, to the temperature of 

 tinization method: while the chemical reagent method 

 has unlimited application to both intrageneric and in- 

 tergeneric differentiation, though the different rea- 

 gents have widely varying values. In comparing 

 these records with those of the systematist it is im- 

 portant to recognize that a slight change in molecular 

 constitution may give rise to very marked changes in 

 properties and that distinction must he made between 

 ih.i' which is definitely established and that which is ten- 

 tative in even the most advanced taxonomic system. All 

 things considered, it is remarkable how close in general 

 is the agreement of the data of these exceedingly dissimi- 

 lar method- of investigation. In fact, they are evidently 



nun ua Ihj i on . i i ! , i ani and w here seeming 



or actual disagreements exist it doubtless will he found 

 that further applications of the physi* tl method 



will demonstrate the reasons. 



Certain of tb i cial 



value in showing the reliability of the i 

 particularly those which are 1 in the groups D 1 



to I mi: 1 1 and \. l i" ! . Kj. i se charts have been given 

 somewhat detailed discussion in Section.- 2 and 3 of 

 Chapter IV. Even a most cm-. on, examination -cpar- 

 atelj and together will demonstrate their taxonomic 

 values, lo group 1 > I to I ' 691, in w Inch are pres 

 the progress of gelatinization at definite time-intervals, 



it is obvious i'r the charai ter ih in 



courses in the individual charts and in the parent-hybrid 

 and the generic groups, that they are quite as dependable 

 as the data of the systematist. Were these >rds not 

 reliable, it seems clear that the curves would not take 

 regular but irregular or zigzag circumlinear 

 in.-iead of being straight or practically straight bines be 

 irregular, etc.; moreover, there would no! be the con- 

 formity of the curves of the reactions with each rea 

 that is found in each set of parent and 

 or in the set.- belonging to each genus, i xci pting in the 

 latter when subgeneric divisions are repr The 



more or less marked subgenei attest the 



value of the method, and if in some instances they may 

 seem to he disproportionate to (hi 

 tematist, tin- maj In- ami doubtless is owing to a gi 

 sensitivity of the physico-chemical m 



The plan adopted in the preparation of Charts K 1 to 

 E Hi, in which composite curves of the reaction-intensi- 

 ties arc exhibited, lias proved in a very large measure 

 successful in eliciting varietal, specie-, subgeneric, and 

 generic peculiarities, hut it- essential defect is to he 

 found in the neglect of differences that were found dur- 

 ing the earlier periods of experiment. In the formula- 

 t ion of thi -e charts terminal data were used — that is, the 

 time of complete or practically complete gelatinizs 



hour or ,ii' the i centage of total starch gelatinized 



within the same period. In many instances such figures 

 may he the same, yet there may I i more or 



marked differences in the progress of gelatinization dur- 

 ing the early periods of the experiments. Notwithstand- 

 ing such defects, there is in general a remarkable di 

 of conformity of these curves h th taxonomic data. 1' 

 should be i 1 with the foregoing the figures pre- 



1 m Table B 1 which give the numbers of very high, 

 high, moderate, low. and very low reactions; tl,,. sums of 

 reaction-intensities: and average reaction-intensities of 

 eai h -Ian h and each parent-hybrid set of star 



Genekal Conclusions dbawh feom Results of 

 mi: Hemoglobin Resj veches. 



The results of the cr\ -lallographic studies of the 

 hemoglobins indicate: that there is a common stni 

 of the hemoglobin mole ule, wh it -never the source of the 

 rlobin; that the crystals of the species of a l'oiius 

 belong to a i rystallographic group which represents a 

 generic type; that the crystals of each if a genus 



when favorably developed can he distinguished from 

 those of another species of the genus; that in some spe- 

 cies there maj he found on,., two, or three forms of hemo- 

 globin, and that this seems to be a generic peculiarity. 



