OF THE LEMURS, BABOONS, AND MAN. 



315 



into groups, united on this face, the groups being parallel growths. Where the parallel 

 growth becomes marked in this way the outline becomes irregular and the composite 

 character of the crystal is apparent (plate 98, fig. 588). The crystals growing together 

 on this flat face (001) often develop into radiating or fan-shaped aggregates, perhaps due 

 to a tendency to twin on the brachydome, but actual twins of this kind were not observed. 

 Pleochroism in some positions is strong, in others is scarcely noticeable; a pale 

 yellowish-red, b =c deep red. Double refraction is strong when a is in the section; extinc- 

 tion is straight in all aspects. In a thick crystal looking along a the biaxial figure was 

 observed. The orientation of the elasticity axes is a =b, b =6, c =a. The acute bisectrix of 

 the optic axes is the axis of greatest elasticity, Bx a =a, and the optical character is negative. 



FIG. 394. Papio porcariua a-Oxyhemoglobin. Fios. 395. 396. 397. Papio porcariua P-Oxyhemoglobin. 

 FIGS. 398. 399. Papio porcariua /3-MethemogIobin. 



fi-Oxyhemoglobin of Papio porcarius. 



Monoclinic: Axial ratio a : b : c =1.732 : 1 : c; ,5=75. 



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



Angles: Prism angle, traces of the prism on the base, edges 110-001 A lTO-001 =60 

 (measurements ran from 59 30' to 60 30' and the average of the series was 60 2') ; angle /?, 

 measured from the prism edge to the base, edge 110-lTO A 001=75. (But compare 

 the /?-methemoglobin angle /? which was 72 30'.) 



Habit tabular on the base in the simple crystals, the tabular crystals rather thin, 

 and generally rather symmetrically developed (text figures 395 and 396), or with two 

 larger and two smaller prism faces. The thickness was from one-fifth to one-eighth of 

 the long diagonal of the plate. The plates aggregate into parallel growths, by extending 

 along the ortho-axis (plate 99, fig. 592) ; and also form twins of the horse-type, the com- 

 posite crystal elongating along the direction of the common prism-base edge (text figure 

 397) . More irregular aggregates are formed, showing radiating and arborescent groupings. 



Pleochroism is strong; a pale yellowish, b scarlet, c deep red. Double refraction 

 strong; extinction on the base is symmetrical; on the edge view, looking along the 

 ortho-axis, the extinction angle is 10 from the trace of the base. The orientation of the 

 optic axes is a A a = 10, in the obtuse angle; b=b; c A <! = 5 , in the obtuse angle. 

 On the basal section one brush of the interference figure is seen, unsymmetrical. On sec- 

 tions that are nearly normal to c the two brushes are seen, the angle IE being about 110. 

 The acute bisectrix of the optic axes is the axis of least elasticity, Bx a =c, and the optical 

 character is hence positive. No crystals of ?--oxyhemoglobin were observed in this species. 



a-Methemoglobin of Papio porcarius. 



Orthorhombic : No axial ratio determinable. 



Forms observed: Macropinacoid 100, brachypinacoid (010), base (001). 



Angles: The angles between the pinacoids were measured as 90 in each case. 



Habit the same as described under a-oxyhemoglobin, which may alter into this 

 methemoglobin by paramorphism. 



The optical characters are different from those of the a-oxyhemoglobin. Pleochro- 

 ism is very strong: a pale yellowish, with a slightly greenish tinge; b = c deep brown. 

 In all sections that show a the double refraction is very strong, in those showing only b 

 and c it is weak; the same is true of the pleochroism. The interference figure is seen 

 looking along c and the traces of it may be seen looking along a also. Looking along c 



