140 CRYSTALLOGRAPHY OF HEMOGLOBIN IN RELATION TO SPECIES. 



Preyer also states that of the 47 species examined and recorded the 

 system of crystallization is known in 10 instances, in only one of which are 

 the crystals accredited to the hexagonal system. In fact, von Lang seems 

 to have been the only professional crystallographer who examined blood 

 crystals up to the time of Preyer, and his descriptions, as has been stated, 

 are very brief. Since von Lang found only two crystal systems, so Preyer 

 concludes there can be but two crystal systems to which the hemoglobin 

 crystals belong. Nevertheless the five ciystal systems mentioned by 

 Preyer as having been recorded by various observers, of which he rejects 

 three, are all represented by us in the hemoglobins included in this research. 

 When we try to find how these investigators arrived at their conclusions 

 as to the crystal system we are met by short, very incomplete descriptions, 

 and we are led to the conclusion reached by Preyer in the case of Funke's 

 monoclinic crystals, that "they support their statements by nothing." 

 The work of von Lang was evidently accurate, although his crystallographic 

 notes are brief; Donogany confirmed von Lang's findings in the case of 

 guinea-pig's crystals, but, as we have already pointed out, he records three 

 angles of a triangle which sum up to 180 46'. The only contribution that 

 has appeared giving the crystallographic constants and an accurate descrip- 

 tion of hemoglobin crystals is that of Schwantka (Zeit. f. physiol. Chemie, 

 1900, xxix, 486) on the oxy hemoglobin of the pigeon, which will be found 

 referred to at length under that species in a later chapter. 



The foregoing is in effect a brief statement of the status of the crystal- 

 lography of hemoglobins at the inception of this research and up to the 

 present time. 



