232 



CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE RODENTIA. 



NORWAY OR BROWN RAT, Mus norvegicus. Plate 54. 



The specimen of blood was received from the Wistar Institute of Anat- 

 omy, Philadelphia. The animal was bled into oxalate, and the blood used 

 immediately. On laking, the blood at once began to crystallize, and within 

 a few minutes a considerable amount of the crystals of oxyhemoglobin 

 had formed in the tube. These were separated by centrifugalization, and 

 from the clear mother-liquor the slide preparations were made. After cover- 

 ing the slides crystals formed rapidly, and they were quite insoluble. The 

 color of the plasma was almost entirely discharged, showing the crystal- 

 lization to be nearly complete. The crystals were small and thin, as in the 

 case of the white rat. They kept well and showed no tendency to dissolve 



N/213 



Fios. 212, 213, 214, 215, 216, 217. Mia noruegicut a-Oxyhemoglobin. 



upon moderate increase of temperature. Even after a month the form of 

 the crystals in the slides had not changed materially. The crystals were 

 oxyhemoglobin. Two forms of the oxyhemoglobin appeared: one pris- 

 matic, and probably orthorhombic, like the white-rat oxyhemoglobin; 

 the other isotropic and apparently isometric, but showing hexagonal out- 

 lines. The prismatic form was the first to appear; the isotropic form 

 developing later may be an isomer of the first form or a mimetic twin. 

 They are distinguished as a-oxyhemoglobin and /3-oxyhemoglobin. 



a-Oxyhemoglobin of Mus norvegicus. 



Orthorhombic: Axial ratio a : b : 6 =0.7829 : 1 : 0.7332. 



Angles: Brachydome angle Oil A Oil =72 30'; the prism angle was not observed, 

 but was calculated as 76 7' ; profile of dome edges over pole when the prism lies on its 

 side, edges 110-011 A TTO-OTl = 120; this is the plane angle of the dome on the prism. 



Habit of the first crystals to form prismatic and generally flattened on two opposite 

 prism faces, making a six-sided tabular crystal elongated on the vertical axis, as is com- 

 mon in the white rat (text figure 212). Some symmetrically developed prismatic crystals 

 were observed that showed the dome termination in symmetrical development; these 

 looked like normal orthorhombic crystals (text figure 213). But the distorted crystals, 



