256 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF THE 



Oxyhemoglobin of Lutra canadensis. 



Monoclinic domatic or clinohedral: Axial ratio a :b:6 =1.2131 : 1 : 0.6794; /9 = 72. 

 Forms observed: Unit prism (110), hemiorthodomes (101) and (T01), clinopinacoid 

 (010), base (001). 



Angles: Traces of the prism on the base, edges 110-001 A 110-001=101; ortho- 

 dome on base T01 A 001=49; prism edge on the base, edge 110-lTO A OOT=72=/3. 

 Habit tabular on the base, the crystal consisting of base (001), unit prism (110) 

 and hemiorthodomes (101) and (10T), the domes appearing at one end of the clino-axis 

 only, indicating clinohedral symmetry (text figures 276 and 277). When the plates are 

 very thin they appear to be orthorhombic hemimorphic, but as they increase in thickness 



they assume a monoclinic habit. In some cases the crystals 

 seem to be the combination (110), (001), (111) (101) (10T), 

 but the unit pyramid was not positively established. The 

 crystals grow singly or in aggregates of two or three together 

 on the base in parallel growth. Twins on the orthodome, or 

 what appears to be a contact of the orthopinacoid on the 

 base, occur; but the orthopinacoid was not observed as a 

 plane. A few crystals of prismatic habit were seen; they 

 seemed to be elongated on the unit prism. The edge views 

 of the plates also appear to be prismatic at first sight, but 

 an inspection of the ends shows the orientation and the 

 clinohedral habit, except when looking along the clino-axis. 

 Pleochroism is strong; a nearly colorless, pale reddish, 

 b rather strong red, c deep red. Double refraction is strong; 

 extinction on the plates normal to the base is symmetrical; 

 on edge, looking along the clino-axis, the extinction is 

 straight. Extinctions up to 15 were observed on edge views, 

 apparently normal to the clinopinacoid. On the base, in 

 convergent light, the biaxial interference figure was observed 

 with widely separated brushes, with the plane of the optic 

 axes normal to the plane of symmetry. The orientation of the elasticity axes is a =b, 

 b A a about 15, c A 6 = 3 about. The brushes of the interference figure are widely 

 separated, passing out of the field upon rotation of the crystal; so it is very probable 

 that the interference figure was seen when looking along the obtuse bisectrix of the optic 

 axes and that the axis of greatest elasticity is the acute bisectrix. The character of the 

 double refraction and of the pleochroism also points to the axis of greatest elasticity as 

 the acute bisectrix of the optic axes; if this is correct the optical character is negative. 



277 



Flos. 276. 277. Lutra canadenlit 

 Oxyhemoglobin. 



PROCYONIDJE. 



KINKAJOU, Cercoleptes caudivolvulus. Plate 68. 



The specimen of blood was received from the Philadelphia Zoological 

 Gardens. It was oxalated and repeatedly frozen, and from the solution 

 thus obtained the slides were prepared as usual. Crystals formed readily 

 at room temperature, but showed a tendency to dissolve upon an increase of 

 temperature. The solution remained rather deeply colored. The crystals 

 were oxyhemoglobin. They were gradually converted by paramorphous 

 change into metoxyhemoglobin after about two weeks. Crystals of reduced 

 hemoglobin appeared in the slides after a few days; they seemed to have 

 the same form as the oxyhemoglobin crystals of the second type, but from 

 the planes developed it would have been impossible to say whether the 

 axial ratio is the same. 



