312 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



following the horse-type of twin, as described in the case of the yellow baboon. In this 

 twin, where the twin-axis is a normal to a common prism-base edge, the two parts gener- 

 ally match exactly on that edge, so that the group is trapezoidal in outline, without 

 reentrant angles (text figure 382). But in many cases the two members of the twin 

 overlap each other symmetrically and produce symmetrical reentrant angles (text 

 figure 383). Trillings produced by three individuals in this position were observed. In 

 these, the composition plane instead of being the base, as is usual in this type of twin, 

 becomes the plane normal to the base, which includes the common prism-base edge; 

 there is thus produced a symmetrical six-pointed star composed of six sections in which 

 the orientation in opposite sectors is the same (text figure 384). In polarized light this 

 became very evident, the opposite sectors extinguishing simultaneously. 



Pleochroism is quite marked; a pale yellowish-red, nearly colorless, b rather strong 

 scarlet-red, c deep red. The extinction is symmetrical on the base and oblique on edge 

 views of the tabular crystal, unless they are in the zone of the orthopinacoid-base. The 

 extinction, when looking along the symmetry axis, is about 14, measured from the 

 profile of the base. The orientation of the elasticity axes is a A a = 14 in the obtuse 

 angle; 6=6; CA<)=6 , in the obtuse angle (taking /? at 70; it is probable this angle is 

 somewhat less and /3 a little more than 70). The interference figure was not observed. 

 The double refraction and the character of the pleochroism appear to indicate the axis 

 of greatest elasticity as the acute bisectrix of the optic axes, Bx a = fl, and this would 

 make the optical character negative. 



ir-Oxyhemoglobin of Papio sphinx. 



Orthorhombic : Axial ratio a : b : t =0.3346 : 1 : 6. 



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



Angles: Unit prism angle 110 A 110=37; prism to base 110 A 001=90. 



386 



587 



Fios. 385, 386. Papio tphinx y-Oxyhemoglobin. Flos. 387, 388. Papio langheldi a-Oxyhemoglobin. 



Habit thin tabular, the crystal consisting of the very long diamond-shaped section 

 of the prism, cut by the base (text figures 385 and 386). The crystals grow from the 

 protein ring and from the cover edge in tufts, attached by one end of the macro-axis; 

 the groups of crystals are divergent or radiating, and the individual crystals are very 

 thin. They did not appear to form definite twins. These crystals, when they begin to 

 appear, develop in great numbers, so that the protein ring and cover edge become 

 fringed with them. They appear to be more soluble than the /J-crystals. 



Pleochroism was not so strong as in the /3-oxyhernoglobin. The colors were : a pale 

 yellowish-red, b deeper red, c rather deep red. Extinction is symmetrical on the basal 

 section and straight on all edge views observed. The orientation of the elasticity axes 

 appears to be a=a, b=b, c=6. No interference figure was observed; but, from the 

 indications of the pleochroism and double refraction, it would seem probable that the 

 axis of greatest elasticity is the acute bisectrix, Bx a = n, and the optical character would 

 then be negative. 



