CHAPTER VII. 



NOTES AND CONCLUSIONS. 



Etpothesis Underlying These Researches. 



These investigations ( Publications Nos. 116, 173, and 

 the present) have as their essential basis the conception 

 that in different organisms corresponding complex 

 organic substances that constitute the supreme struc- 

 tural elements of protoplasm and the major synthetic 

 products of protoplasmic activity are not in any case 

 absolutely identical in chemical constitution, and that 

 each substance may exist in countless modifications, each 

 modification being characteristic of the form of proto- 

 plasm, the organ, the individual, the sex, the species, 

 the genus, etc., and that the possible number of modified 

 forms of each substance is in direct relationship to the 

 complexity of the molecules. 



Kxi'i.oKATORY Character — Evidence in Support 

 of the Hypothesis, Etc. 



These inquiries have for certain reasons been 

 practically of a purely exploratory character and there- 

 fore no serious attempt has been made to do more than 

 gather sufficiently convincing evidence to amply sustain 

 the hypothesis and thus lay a satisfactory foundation for 

 subsequent inquiries. It is obvious, from the results of 

 each of these studies, that considering the difficulties met 

 in pioneer investigations the measure of success has been 

 beyond that which should reasonably have been expected. 



Hemoglobins from 107 species were examined, 

 mostly from mammals, including representatives of 

 Pisces, Batrachia, Aves, Marsupialia, Edenta, Sirenia, 

 ITngulata, Eodentia, Otariidia, I'hocida?, Mustelidoc, 

 Procyonidse, Ursidse, Canidse, Felidse, Viveridae, Insec- 

 tivora, f'hiroptera, and Primates. The number seems 

 large in comparison with the numbers studied by various 

 previous investigators, yet it is an insignificant fraction 

 of the number existent in vertebrates and invertebrates. 

 Moreover, in antecedent investigations the crystallo- 

 graphic examinations were, with scarcely an exception 

 of a single hemoglobin, limited to geometric form, while 

 in the studies embraced in this series of researches both 

 geometric form and optic reactions were recorded, the 

 latter being here very important and often as distinctive 

 and as exact in differentiation as chemical reactions. 



The starches studied have been so numerous as to 

 cover a far broader field, including in the preceding 

 research 300 that represent 105 genera and 3. r > families, 

 and in the present researeb 17 sets of parent- and hybrid- 

 stocks, and representing 17 genera and 7 families. The 

 total number examined compared with those available 

 Eor similar investigation is. as in the hemoglobins, an 

 exceedingly small or almost negligible fraction. 



Not only have the hemoglobins and starches been 

 scarcely more than touched, but there remains an enor- 

 mous list of complex metabolites included among the 

 proteins, fats, carbohydrates, enzvmes, coloring matters, 

 eholesterols, organic acids, alkaloids, etc., and also a 

 very large number of compounds, which as yet have been 

 370 



subjected to extremely little or absolutely no investi- 

 gation in regard to their constitutional properties in rela- 

 tion to biological source. Some or even many of these 

 metabolites are not unit substances — that is, they are 

 combinations, physical or chemical, of like or unlike sub- 

 stances. Moreover, there are derivatives of many of 

 these primary or initial substances — for instance, the 

 crystalline chlorophyls (ethylchlorophylides) — that are 

 most promising for such investigations. An unlimited 

 field of investigation in both material and promise 

 is opened by the facts that probably every sub- 

 stance, elementary and compound, may exist in more 

 than one form; that when molecules are associated 

 during polymerization there is chemical combination, 

 and that in these combinations the arrangements of the 

 components in the three dimensions of space may yield 

 different forms of the same substance (as in water), or 

 entirely different substances (as in the polymerization 

 of formaldehyde to form dextrose) ; that the possible 

 number of stereoisomer^ forms increases directly with 

 the complexity of the molecular organization; and that 

 in all probability these various stereoisomer^ forms of 

 substances produced by protoplasmic activity are spe- 

 cifically modified in relation to biologic origin. 



aIethods Employed axd Recommended. 



The crystallographic method used in the investiga- 

 tions of the hemoglobins is, in so far as the require- 

 ments of these investigations are concerned, not only 

 exact but also a very sensitive means of differentiation 

 of different forms of these substances. Differences in 

 chemical constitution can readily be demonstrated which 

 as yet arc too obscure for detection by any known chemi- 

 cal procedures; differences have been shown that can not 

 be brought out by any of the biologic tests ; repeated 

 experiments with the hemoglobins from different indi- 

 viduals of the same species have yielded practically or 

 absolutely the same results; biologic differences elicited 

 by this means are in accord with the data of the syste- 

 matist wherever the latter is not open to question ; and 

 these records have had confirmation in the results of 

 anaphylactic reactions. The methods for differentiat- 

 ing stereoisomers are with rare exceptions quite crude, 

 but even those which are inexact may be not only checks 

 upon each other but also collectively and even individ- 

 ually be of much usefulness in such investigations. It 

 was pointed out that differences had been recorded in the 

 hi moglobins from different species in their solubilities, 

 crystallizabilities, water of crystallization, extinction co- 

 efficients and quotients, and decomposability; and it is 

 evident, inasmuch as differences that may lie exhibited 

 by one method may not be brought out by another, or in 

 varying degree, that much is to be gained by the use of 

 many or all methods. Very much is possible by means 

 of further development of biologic tests. 



Tn the differentiation of starches, both in the pre- 

 ceding and present researches, the methods employed 



