PRELIAIINARY REPORT UPON A CRYSTALLOGRAPHIC 



STUDY OF THE HEMOGLOBINS: A CONTRIBUTION 



TO THE SPECIFICITY OF CORRESPONDING 



VITAL SUBSTANCES IN DIFFERENT 



VERTEBRATES. 



By EDWARD T. REICHERT and AMOS P. BROWN. 



(Read April 24, 190S.) 



The primar}- object of this research was to determine whether 

 or not corresponding proteins are identical in different species. 

 Hemoglobin was selected as a favorable substance to begin such a 

 study upon because of its being readily obtained in a state of com- 

 paratfve purity, and, in many cases, readily isolated in crystals. 

 When a sufficient supply of blood was available, it was nearly always 

 possible, by the use of suitable methods, to produce well formed 

 crystals that could be satisfactorily examined and studied by the 

 method adopted. The crystallographic method was chosen because, 

 by its means, differences in substances may be observed that would 

 elude the ordinary methods of analysis employed by the chemist. 

 Moreover, it is comparatively rajjid and therefore well adapted to 

 the study of a substance so liable to alteration as hemoglobin. In 

 the method employed it was not even necessary to remove the crys- 

 tals from the mother li(|uor for examination. In studying the crys- 

 tals and measuring the crystallographic constants the petrographic 

 microscope was used, but in the case of these crystals of hemoglobin 

 we have this advantage over the petrographer in his examination 

 of rock sections, in that these crystals arc not imbedded in an opacjue 

 or semi-opaque matrix, but are in a trans])arent medium and are 

 usually isolated from each other. Moreover, hundreds and often 

 thousands of crystals are open to observation in a single slide, 

 and tliese present almost all possible orientations, allowing the opti- 

 cal cliaracters to be determined with nuich greater accuracy than 



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