184 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



Angles: Traces of unit prism on base, edges 110-001 A 110-001=95 (85); of 

 the clinoprism on base, edges 230-001 A 230-001=75 (105); base to prism edge 

 (6 A 6) 001 A 110-110=90; base to prism edge (6 A a) 001 A 110-lTO=/3 = 55. 



Habit short prismatic to tabular, the tabular crystals formed by the unit prism 

 and base being nearly square in outline (text figure 87). The more prismatic crystals 

 showed the unit prism and base, and varied from equidimensional blocks to prisms with 

 a length equal to 3 to 4 times the thickness. The prismatic crystals were sometimes 

 the clinoprism (230) (text figure 88), but combinations of this prism with the unit prism 

 were not observed. The crystals, especially those of the prismatic type, aggregated 

 themselves in stellate groups by growing together in the orthodome zone, but definite 

 twins were not observed. Crystals growing along the cover edge were often elongated 

 into long, prismatic-looking forms, growing in tufts. These were usually edge views 

 of the plates, which also occasionally aggregated together by uniting on the base, or 

 on faces vicinal to the base, but without definite twinning orientation. 



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a 



Flos. 84,85. Thylacynua cynocephtilus a-Oxyhemoglobin. FIG. 86. Thylacynug cynncephahia 0-Oxyhemoglobin. 

 FIGH. 87.88. Trichositrua vulpecula Oxyhemoglobin. 



On account of the deep color of the plasma the pleochroic colors could not be defi- 

 nitely observed, but the crystals are strongly pleochroic, with absorption c > 6 > a. 

 On the base, the crystal extinguishes symmetrically, with the axis of greater elasticity 

 bisecting the acute angle of the plate. On the clinopinacoid sections the extinction is 

 oblique, making an angle of 9 with the edge 010-001 or with the clino-axis, a, in the 

 obtuse angle. The plane of the optic axes is normal to the plane of symmetry and a =b. 

 The orientation of the other elasticity axes is, 6 A a =9 in the obtuse angle, the extinc- 

 tion angle; and c A 6 = 26, in the obtuse angle. Traces of the brushes of an interfer- 

 ence figure show on some of the plates that are tilted, with the orientation as above for 

 the elasticity axes. On the clinopinacoid sections the interference figure shows when 

 looking along a, the brushes being only slightly separated. The acute bisectrix is hence 

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



RAT-KANGAROO, &pyprymnus rufescens. Plates 21 and 22. 



The specimen was received from the National Zoological Park at 

 Washington. The blood was putrid, but, being collected in oxalate, was 

 liquid. The contents of the tube were centrifugalized. The separated cor- 

 puscles were then laked with ether and again centrifugalized, and slides 

 prepared in the usual manner. Crystallization was rapid; the crystals 

 formed readily at room temperature and appeared to be relatively insoluble. 

 The color of the solution was almost discharged, showing that the crystal- 

 lization was very complete. Negatives were made within 5 hours after 

 the slides were prepared. The crystals were oxyhemoglobin as determined 

 by the spectroscope. 



