OF THE LEMURS, BABOONS, AND MAN. 



309 



fl-Oxyhemoglobin of Papio babuin. 



Monoclinic: Axial ratio a : b : 6 =1.6808 : 1 : 6; [3=72 to 72 30'. 

 Forms observed: Unit prism (110), orthopinacoid (100), base (001). 

 Angles: Traces of prism on base edges 110-001 A lTO-001 =60 30' actual angle; 

 base to prism edge, or to orthopinacoid, 001 A edge 110-lTO =72 to 72 30' =/?. 



373 



376 



374 

 Fias. 372, 373. 374, 375, 376. Papio babuin 0-Oxyhemoglobin. 



Habit tabular on the base, usually rather thin, but also thick tabular (text figures 

 372 and 373); and, in some cases, becoming prismatic by development of (110). The 

 tabular crystal consists of the unit prism (110) and base (001) only, unless the pseudo- 

 plane (010) is formed by contact with slide and cover; but the prismatic crystal frequently 

 develops also the orthopinacoid, (100), and then the combination is (110), (100), (001) 

 (text figure 374) ; the crystal in this type of prismatic development becomes almost a 

 hexagonal prism but with oblique ends. When the prism and base occur alone, in equi- 

 librium, the form assumed is that of a regular rhombohedron. 



Twinning is normal in this /3-oxyhemoglobin; it follows the horse- type of twinning, 

 in which the axis of the twin is normal to a prism-base edge, and the composition face 

 is generally the base (text figure 375), but may be a plane normal to the base, and includ- 

 ing the prism-base edge (text figure 376). The tabular crystals showing this twin, and 

 with the base as composition face, become quite similar in appearance to the horse twin; 

 they tend to form trillings or more complicated groups in the same way; but no very 

 regular groups result, such as the six-rayed stars seen in twins of the oxyhemoglobin 

 of Papio sphinx, the guinea baboon. 



Pleochroism on plates is strong; a colorless or nearly so, b deep red, c very deep 

 red. Double refraction is strong; extinction is symmetrical on the plate, but oblique on 

 the side view, looking along the symmetry axis. The extinction angle was not exactly 

 obtained, but ran near 12 to 14. Calling it the mean 13, the orientation of the elasticity 

 axes becomes a A a = 13, in the obtuse angle ; b=b; c A <J=4 30' in the obtuse angle. 

 In the twins, positions on edge are often seen, in which the two extinctions are nearly 

 symmetrical with the composition plane, and they then run near 8 to 10. The interfer- 

 ence figure was not observed. Apparently the acute bisectrix is the axis of least elasticity, 

 Bx a = c. This would make the optical character positive. 



f-Oxy hemoglobin of Papio babuin. 



Orthorhombic: Axial ratio a : b : 6 =0.5317 : 1 : c, or f (0.3544) : I : 6. 



Forms observed: Unit prism (110), base (001). 



Angles: Prism angle 110 A 110=56 (about); prism to base 110 A 001 =90 

 (about) . 



Habit long prismatic along the vertical axis, usually terminated by the base (text 

 figure 377) ; but the crystals very soluble and the ends usually lost by solution. The 

 crystals had to be observed in the cold; but, even with this precaution, satisfactory 

 measurements of the terminal plane with respect to the prism were not obtained. The 

 crystals grew singly or in loose aggregates. Twins were not observed. Some of the 

 crystals seemed to show an oblique terminal plane, but, as stated, the ends dissolved 

 so rapidly on slightly warming the slide that this was not confirmed. 



