166 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF AVES. 



Habit tabular, the square tables (text figures 40 and 41) aggregated into groups 

 by piling up of the plates or perhaps by twinning on an axis normal to the edge (110-001); 

 also by what appears to be twinning on a dome; the crystals usually occur in isolated 

 clusters. Sometimes skeleton crystals are seen that look tetragonal, but are orthorhombic 

 according to their optical characters. 



Pleochroism is not very marked, hardly noticeable on the flat view, but stronger 

 on the edge view, especially when looking along 6. Orientation of the elasticity axes, 

 a =6, b=a, (=6. The plane of the optic axes is the macropinacoid; Bx a =a, hence 

 the crystal is optically negative. Absorption c > b > a. On looking along a in conver- 

 gent light the interference figure is seen with the brushes rather widely separated. 



QUAIL, Colinus virginianus. Plate 12. 



The blood was obtained from the living bird, and prepared in the usual 

 manner. Corpuscles were used for extraction of the oxyhemoglobin which 

 was tested by the spectroscope. The crystals form sparingly and melt 

 readily at a little above C. 



Oxyhemoglobin of Colinus virginianus. 



Orthorhombic: a : b : 6 =0.9657 : 1 : t. 



Angles: 110 A 110=88 (normals); 110 A 001=90. 



Forms observed: Prism (110), base (001). 



Habit thin to thick square tabular; the tables consisting of the above combination 



and varying in thickness from one-fourth to one-half of 

 the width of the plate (text figures 42 and 43) ; the cry- 

 stals grew singly and in groups, but did not grow in the 

 radiating form of the chicken oxyhemoglobin. Perhaps 

 they twin on the axis normal to the prism-base edge, as 

 the plates pile up on the base and overlap somewhat 

 irregularly. 



Examined on (001), the crystals show no perceptible 

 pleochroism; on edge the pleochroism is weak, but notice- 

 able. The angle of the prism is so near 90 and the plates 

 so irregular, due to overlapping, etc., that it is difficult to 

 determine the exact orientation of the optic axes; the 

 extinction is straight on the edge view and symmetrical 

 on the (001) view. One of the diagonals is readily made 

 out by the quartz-wedge to be an axis of greater elastic- 

 ity than the other, but on edge views it is seen that c=<!. 

 The plane of the optic axes is probably the macropina- 

 coid, and when looking along a (in edge view) the inter- 

 ference figure is seen, showing Bx a a, and the optical 

 Absorption is c = b (nearly) > a. Pleochroism: c and 6 



43 



Flos. 42, 43. Colinus virginianut Oxy- 

 hemoglobin. 



character is hence negative. 

 deep red, a paler red. 



GUINEA-FOWL, Numida melcagris. Plate 12. 



The blood was obtained by bleeding the living bird and was oxalated 

 and prepared in the usual manner. Crystals formed readily and did not 

 appear to be very soluble, as they remained in perfect condition at room 

 temperature. The oxyhemoglobin crystallizes readily at ordinary temper- 

 ature in well-formed crystals, in contrast to the crystals obtained from 

 the bloods of most of the birds examined. 



