SPECIFICITY OF PROTEINS AND CARBOHYDRATES 
93 
genus or species or sex as the data of the systemist, and to be deter- 
minate of the specificity of the protoplasm itself. 
It follows from what has been stated that haemoglobin may not 
only exist in nature in countless forms, but also that each form may 
be absolutely characteristic of the genus and species. 
In an investigation of the haemoglobins it was found that these 
substances exhibit differences in solubility, decomposibility in relation 
to putrefactive organisms, quantity of water of crystallization,, 
decomposibility in relation to various chemical reagents, extinction 
coefficients and quotients, crystallizability, and form and habit of 
crystallization. The characters of the crystals were especially studied,, 
particularly the forms and habits of crystallization, the peculiarities 
of twinning, and the "optical reactions," which latter as determined 
by the aid of the polarizing microscope may be found analytically to 
be as definite and exact as the reactions obtained by the conventional 
methods of the chemist. It was found, for instance, in these studies 
which embraced examinations of specimens of haemoglobins from over 
ICQ species representing many genera and families: 
1. That there is a common structure of the haemoglobin molecule 
whatsoever the source of the haemoglobin. 
2. That the crystals of the species of any genus belong to a 
crystallographic group which represents a generic type. 
3. That the crystals of each species of a genus when favorably 
developed can be distinguished from those of other species of the genus. 
4. That the crystals of different generic groups differ as definitely 
and specifically as those of crystalline groups of mineral substances 
differ chemically, and as generic groups differ zoologically or botan- 
ically. 
5. That by means of the peculiarities of haemoglobins phylogenetic 
relationships can be traced, as has been found in the case of the bear 
and certain other animals. 
Subsequent studies with other substances, especially with animal 
and plant proteins, a large number of starches, some glycogens and 
chlorophyls and other complex metabolites, have ehcited confirmatory 
results and even extended the data of the haemoglobin research. 
The investigations with the starches were necessarily carried on 
by methods that are quite different from those employed in the study 
of the haemoglobins. Although the starch granule is a spherocrystal 
that lends itself to crystallographic study, very little can be learned 
