OF THE CATS AND CIVETS. 



295 



able, except in the prismatic type of crystals. In the isometric type it was absent, which 

 would indicate mimetic twinning. The thin plates were not pleochroic. The change 

 in color was very slight in the prismatic crystals, mainly a variation in shade of color. 

 Extinction was straight in the prismatic crystals; the other types did not have any 

 action upon the polarized light. The interference figure was not observed. The orienta- 

 tion of the elasticity axes was a=c, b=6, c=a; the elasticity of a and b was nearly 

 equal. The tabular crystals were too thin to show any polarization characters, but did 

 not give an interference figure. It is therefore probable that the acute bisectrix of the 

 optic axes is the axis of least elasticity Bx a = c; this makes the optical character probably 

 positive. 



Reduced Hemoglobin of Lynx rufus. 



Orthorhombic: Axial ratio a : b : 6 =0.9863 : 1 : 0.3914. 



Forms observed: Unit prism (110), macroprisms (320), (210), brachydome (Oil), 

 brachypinacoid (010). 



Angles: Unit prism 110 A 110=89 15'; macroprism 320 A 320=66 45'; macro- 

 prism 210 A 210=52 30'; brachydome Oil A Oil =42 45'. The angle of prism to 

 brachypinacoid was not measured. 



' C 



348 



349 



350 



351 



FIGS. 348, 349, 350, 351. Lynx rufut Reduced Hemoglobin. 



Habit at first (a) the macroprism (210) and the dome (Oil) (text figure 348) elon- 

 gated on the prism, which is very variable in length, the ratio of length or thickness 

 varying from 4 : 1 to 20 : 1 or more. Later crystals (b) showing the prism (320) with 

 (010) and (Oil) appear (text figure 349); and also, sparingly, crystals (c) consisting of 

 the unit prism (110) and the dome (Oil) only (text figure 350). These last (c) are usually 

 short with ratio of length to thickness of 3 : 1 or less; but the other two types (a) and 

 (b) are more frequently long. Twinning is very common in these crystals; apparently 

 the twins are on the unit pyramid as a rule (text figure 351), but some seem to be on a 

 brachydome. Irregular radiating groups of crystals, and second growths of small crystals 

 in tufts on the larger crystals, are very frequently observed. A very common habit is 

 the unequal development of the two brachydome faces; one being sometimes almost 

 suppressed, while the other is greatly developed on the two ends of the crystals; these 

 are usually the faces on one side as Oil, Oil; but when only one end of the crystal appears, 

 this oblique termination of the single dome face produces a very monoclinic aspect. 

 In twins it is common to see the oblique ends arranged symmetrically with respect to 

 the twin plane. In some cases a long pointed pyramid, perhaps (991) as in the oxyhemo- 

 globin, was observed. The angle of its edges over the pole was about 30, but the measure- 

 ment was very inexact. 



The color of the crystals is the usual purplish-red of reduced hemoglobin. Pleo- 

 chroism is very pronounced; a pale lilac, b purplish, rather pale, c rose-purple, much 

 deeper than b. Double refraction is strong and extinction is straight or symmetrical in 

 all axial aspects. On cross-sections of the prism the biaxial interference figure is seen 

 in convergent light, with widely separated brushes. The orientation of the elasticity axes 

 is a = 6, 6 = a, c = i. The plane of the optic axes is the macropinacoid and the acute bisectrix 

 of the axes is the axis of least elasticity, Bx a = c. The optical character is hence positive. 



