258 CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF THE 



Reduced Hemoglobin of Cercoleptes caudivolvulus. 



Orthorhombic : Axial ratio not determinable. 



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



Angles: Macropinacoid to base 100 A 001=90. 



Habit the same as the square tabular form of the type (b) crystals of the oxyhemo- 

 globin (text figure 279), growing in the same parallel growth aggregates. The plates 

 were thin and were not observed on edge. 



Pleochroism on the brachypinacoid strong, as in the oxyhemoglobin; a rose-pink, 

 c deep rose-red to purplish-red. 



These may be only paramorphs after the oxyhemoglobin plates, type (b) crystal. 



CACOMYXL OR CACOMISTLE, Bassariscus astuta. Plate 68. 



The specimen of blood was received from the Philadelphia Zoological 

 Gardens; and, while it had a slight odor, was in fairly fresh condition. 

 The blood was oxalated, but the method of laking was not recorded. It 

 was not centrifugalized. The crystals formed quite readily, and inside of 4 

 hours after the preparations were made satisfactory photomicrographs 

 were obtained. The crystals do not appear to be very soluble, and retain 

 their sharp outlines when brought from the cold into a warm room. The 

 crystals were oxyhemoglobin. 



Oxyhemoglobin of Bassariscus astuta. 



Orthorhombic: Axial ratio a : b : c =0.7399 : 1 : 0.3939. 



Forms observed: Unit prism (110), brachydome (Oil), brachypinacoid (010). 



Angles: Unit prism 110 A 110=73; brachydome Oil A Oil =43; brachypina- 

 coid to brachydome 010 A Oil =68 30'. 



Habit prismatic on the vertical axis, the crystal consisting of the unit prism, brachy- 

 pinacoid, and brachydome (text figure 280), the brachypinacoid being in some cases very 

 small or absent. The crystals are generally very perfect and symmetrically developed, 

 with smooth planes and without striations. They occur as individuals, scattered through 

 the slides, and also twinned; but do not aggregate in any regular form aside from the 

 twins. They vary much in size and in ratio of length to thickness; generally .this ratio 

 is about 10 : 1, but short forms occur in which it runs down almost to 1 : 1. Twins occur 

 with the unit pyramid (111) as the plane of twinning (text figure 281), also with a brachy- 

 dome of about (031) as the plane of twinning (text figure 282). In the scattered crystals 

 in the slides, a large number are seen intersecting at other angles, which may be twins; 

 but the angles appear to vary so much that the crystals are probably in accidental 

 orientation with each other. The crystals do not form radiating or parallel groups. 



The color of the crystals in ordinary light is blood-red; in plane polarized light 

 from one nicol they are strongly pleochroic in all aspects. The colors are: a nearly color- 

 less, b rose-pink, c deep rose-red. Double refraction is strong and the extinction is straight 

 in all side views of the prism and symmetrical in cross-sections on the base. The orienta- 

 tion of the elasticity axes is a = 6, 6= a, c = c. The plane of the optic axes is the macro- 

 pinacoid. On basal sections, and on the brachypinacoid, the biaxial interference figure 

 may be observed, with the brushes widely separated; but the figure seen on the basal 

 section shows that the axis of least elasticity is the acute bisectrix Bx a =c, and the optical 

 character is hence positive. 



URSIDiE. 

 BLACK BEAR, Ursus americanus. Plates 69 and 70. 



Two specimens of blood were examined, one from the Pittsburg Zoo- 

 logical Garden (specimen I) and one from the Philadelphia Zoological 

 Garden (specimen II). Both specimens had been collected in oxalate in our 



