186 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



placed in the tube. Ether added to lake the blood appeared to increase the 

 precipitate of amorphous granular matter, and centrifugalizing did not 

 entirely free the blood from this precipitate. The crystals formed readily 

 at ordinary room temperature and did not appear to be very soluble. Pho- 

 tographs could be made inside of 4 hours after the slides were prepared. 

 Examination with the spectroscope showed the crystals to be oxyhemo- 

 globin. 



Oxyhemoglobin of Macropus giganteus. 



Monoclinic: Axial ratio a : 6 =1 : 0.497; /?=87 (93). 



Forms observed: Orthopinacoid (100), clinopinacoid (010), base (001); also an 

 orthodome (T01). Some crystals apparently showed a square prism (110) in place of the 

 two vertical pinacoids; this was not clearly made out. 



Angles: 100 A 001 -0=-87 (93); 001 A 010=90; 100 A 101 =66. The posi- 

 tive hemiorthodome (T01) was also observed as a plane of twinning with angle between 

 the (! axes of the twin of 48 30' as measured. This gives the angle 100 A T01 =65 45'. 



Habit lath-shaped crystals, consisting of orthopinacoid (the principal plane) and 

 clinopinacoid; the two forming a flattened prismatic crystal elongated along the vertical 

 axis and terminated by the base (001) (text figure 95). They, being flattened on (100), 

 generally present this aspect and hence appear to be terminated by a plane normal to 

 the length, but the square end is produced by the aspect in which the crystal is usually 

 presented, and on an edge view, looking along the 6-axis, the end is seen to be oblique. The 

 orthodome was seen in a few crystals only. The lath-shaped crystals aggregate into sheaf- 

 like bundles and stellate radiating groups, and also grow singly. Twins on the orthopina- 

 coid (100), gypsum type, were occasionally seen (text figure 96) and one distinct twin on 

 the hemiorthodome (T01) was observed with the angle as given above (text figure 97). 



Pleochroism is very pronounced; a pale pink, b rose-pink, c deep rose-pink. Extinc- 

 tion is straight or nearly so in both side and edge views. The end view was not seen. The 

 orientation of the elasticity axes is c=<5, a =6, b A a =3, in the obtuse angle; the axial 

 plane is normal to the plane of symmetry. No interference figure could be observed, 

 but indications seemed to show that Bx a =c, and the optical character is hence probably 

 positive. 



" J, 



<*, 



100 



101 



Fioa. 95, 9G. 97. Macropia eigant*\a Oxyhemoglobin. FIOB. 98, 99, 100, 101. Pilrogalt sp. Oxyhemoglobin. 



ROCK-KANGAROO, Petrogale sp. Plate 23. 



The specimen was received in July and kept frozen in the original col- 

 lecting tube until examined. The blood was full of a granular precipitate 

 which did not separate on centrifugalizing. The blood had been oxalated 

 when collected and was not ether-laked. The slides were prepared in the 



