362 



APPLICATIONS OF RESULTS OP RESEARCHES. 



complex molecules of the members of the group of 

 monosymmetric double sulphates. 



4. The crystallographic specificity in relation to spe- 

 cies. The crystals of each species of a genus, when they 

 are favorably developed for examination in the polariz- 

 ing microscope, can usually be distinguished from each 

 other by definite angles and other properties, while 

 preserving the isomorphous character belonging to the 

 genus. Where, on account of difficulty of measurement, 

 the differences can not be given a quantitative- value, 

 variations in habit and mode of growth of the crystals 

 often show specific differences. 



5. The occurrence of several types' of oxy-hemoglobin 

 in members of certain genera. In some species the oxy- 

 hemoglobin is dimorphous and in others trimorphous. 

 Where several types of crystals occur in this way in the 

 species of a genus the crystals of each type may be 

 arranged in an isomorphous series. In other words, 

 certain genera as regards the hemoglobins are isodimor- 

 phous and others isotrimorphous. 



6. When orders, families, genera, or species are well 

 separated the hemoglobins are correspondingly mark- 

 edly differentiated. For instance, so different are the 

 hemoglobins of Aves, Marsupialia, Ungidata, and Ro- 

 dentia that there would be no more likelihood of con- 

 founding the hemoglobins than there would be of mis- 

 taking the animals themselves. Even where there is 

 much less zoological separation, as in the case of the 

 genera of a given family, but where there is well-marked 

 zoological distinction, the hemoglobins are so different as 

 to permit readily of positive diagnosis. When, however, 

 the relationships are close the hemoglobins are corre- 

 spondingly close, so that in instances of an alliance such 

 as in Canis, Yulpes, and Urocyon, which genera years ago 

 were included in one genus (and doubtless correctly) 

 the hemoglobins are very much alike, and in these cases 

 they may exhibit closer resemblances than may be found 

 in general in specimens obtained from well-separated 

 species of a genus. 



So distinctive zoologically are these modified forms 

 of hemoglobins that we had no difficulty in recognizing 

 that the common white rat is the albino of Mus nor- 

 vegicus (Mtis norvegicus cdbus Hatai) and not of Mus 

 rattus, as almost imiversally stated, and that Ursidse 

 are related to Phoeidae (as suggested by Mivart 30 years 

 ago), but not to Canidse, as stated in modern works on 

 zoology. Moreover, we were quick to detect errors in 

 labeling, as, for instance, when a specimen marked as 

 coming from a species of Papio was found to belong to 

 one of the Pelidae. Generic forms of hemoglobin when 

 obtained from well-separated genera are, in fact, so dif- 

 ferent in their molecular structures that when any two 

 are together in solution they do not fuse to form a single 

 kind of hemoglobin or a homogeneous solution, but con- 

 tinue as discrete disunited particles, so that when crystal- 

 lization occurs each crystallizes independently of the 

 other and without modification other than that which is 

 dependent upon such incidental conditions as are to be 

 taken into account ordinarily during crystallization. 

 Thus, the hemoglobin of the dog crystallizes in rhombic 

 prisms which have a, diamond-shaped cross-section ; that 

 of the guinea-pig in tetrahedra ; that of the squirrel in 

 hexagonal plates; and that of the rat in elongated six- 

 sided plates. When any two of these hemoglobins are 



together in solution and crystallization occurs, each ap- 

 pears in its own form. Such phenomena indicate that 

 the structures of the hemoglobin molecules are quite 

 different; in fact, more differentiated than the mole- 

 cules of members of an isomorphous group of simple 

 carbonates, such as the carbonates of calcium and mag- 

 nesium, which in separate solutions crystallize in rhom- 

 bohedrons whose corresponding angles differ 2° 15', but 

 in molecular union, as in the mineral dolomite, crystal- 

 lize as a single substance which has an intermediate 

 angle. 



Upon the basis of our data it is not going too far to 

 assume that it has been satisfactorily demonstrated theo- 

 retically, inferentially, and experimentally that at least 

 this one substance (hemoglobin) may exist in an incon- 

 ceivable number of stereoisomeric forms,* each form 

 being peculiar to at least genus and species and so de- 

 cidedly differentiated as to render the "hemoglobin 

 crystal test" more sensitive in the recognition of ani- 

 mals and animal relationships than the " zooprecipitin 

 test." 



Subsequent to the research referred to, investigations 

 have been pursued in the study of hemoglobins from 

 various additional sources, especially from representa- 

 tives of Primates, with the result in the latter case of 

 finding indubitable evidence of an ancestral alliance of 

 man and the man-like apes. 



More or less elaborate studies by crystallographic 

 and other methods have also been made with other albu- 

 minous substances and with starches, glycogens, phyto- 

 cholesterins, chlorophyls, and other complex synthetic 

 products of animal and plant life, especially with 

 starches, of which over 300 specimens were examined, 

 obtained from representatives of a considerable number 

 of families, genera, species, varieties, and hybrids. In 

 all of these investigations the results are not only in full 

 accord with those of the hemoglobin researches but, in 

 some instances of broader significance, because by better 

 methods of differentiation it was found possible to recog- 

 nize not only peculiarities as regards genus or species, 

 but also varieties and hybrids, and even to trace in hy- 

 brids with marked definiteness the transmission of 

 parental characteristics. 



Summing up the results of these independent but 

 interwoven researches, we find that the modified forms 

 of each of these substances lend themselves to a very 

 definite system of classification, and to one that is in 

 general accord with that of the botanist and zoologist, 

 that is, each genus is characterized by a distinctive type 

 of hemoglobin, albumin, starch, etc., as the case may be, 

 which may be designated the generic-type ; every species 

 of the genus will have a modification of this type, which 

 is a species-type, or generic primary sub-type ; and every 

 variety of a species will have a modification of the species- 

 type, that is a variety-type, or generic secondary sub- 

 type, or species sub-type. In fact, it seems clear that 

 with revisions of present classifications that are certain 

 to come there will be found definite family types ; and, 

 moreover, that with improved methods of differentiation 

 there will be discovered positively distinctive sex- and 



*Even if we assume that the different forma are not, strictly 

 speaking, stereoisomers it must be admitted that hemoglobin exists 

 in forms that are specifically modified in relation to genera and 

 species. 



