170 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF AVES. 



photographed, and reduced hemoglobin developed along with the oxy- 

 hemoglobin. Other preparations were made from the clear fluid, prepared 

 as above; and were recorded while containing only oxyhemoglobin. Upon 

 long standing, the crystals in the slides were converted into metoxyhemo- 

 globin. These crystals were all very soluble, but the oxyhemoglobin much 

 more so than the others, and when removed from the cold into a warm room 

 the crystals of oxyhemoglobin dissolved rapidly. Owing to this ready solu- 

 bility the examinations had to be made in a room kept a temperature near 

 the freezing-point. Measurements were made of the three forms observed, 

 and the substantial identity in form of the oxyhemoglobin, reduced hemo- 

 globin, and metoxyhemoglobin was made out. 



Oxyhemoglobin of Corvus americanus. 



Monoclinic: Axial ratio a : b : t = \ : b : 1.044; /? = 50. 



Forms observed: Orthopinacoid (100), clinopinacoid (010), base (001),orthodome 

 (T01), and a prism (mm 0). 



Angles: 100 A 001=^ = 50 (130); 100 A 010 = 90; 001 A 010 = 90; TlO A 001 

 = 63. The angle of the flat prism (clinoprism) was not observed. 



a 



V> 



Flos. 54, 55, 56. Corrui americanua Oxyhemoglobin. Flo. 57. Corvus americama Reduced Hemoglobin. 



Habit thick or thin tabular by development on the plane of symmetry (010), the 

 usual crystal showing only the three pinacoids, but elongated along the vertical axis 

 (text figure 54) and some crystals showing a clinoprism in this zone. In a few crystals 

 the full combination was observed, of three pinacoids, prism, and positive hemiorthodome 

 (text figure 55), and some showed this orthodome without the prism. The direction of 

 the vertical axis is shown by inclusions of the mother-liquor and by cracks parallel to 

 the vertical axis. Perhaps a prismatic cleavage is indicated. "Twins" form with a 

 twinning axis about the normal to the orthodome and with the orthopinacoid of one 

 member in contact with the base of the other member (text figure 56). 



Pleochroism strong; a pale yellow, b and c deep red. In thick crystals the color 

 of a rises to pale yellowish-red. All show the oxyhemoglobin spectrum. Extinction on 

 the edge view, zone of (100) and (001) is straight; on the plane of symmetry (010) the 

 extinction is oblique, nearly bisecting the acute angle of the plate, a A 6=22, the extinc- 

 tion angle, measured from the edge 100-010. Orientation of the elasticity axes is a A t = 

 22 in the acute angle, BA a =62 in the obtuse angle, c=6; the plane of the optic axes 

 is normal to the plane of symmetry. On the clinopinacoid the two brushes of the inter- 

 ference figure are seen, but pass out of the field; the acute bisectrix, therefore, probably 

 lies in the plane of symmetry and Bx n =a, or the crystal is optically negative. It will be 

 noticed that the symmetry is nearly orthorhombic, but the parting or cleavage along 

 the axis t and the habit of the crystal, especially when the prism is developed, all indicate 

 monoclinic symmetry. 



