CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE UNGULATES. 209 



parallel grouping with the vertical axis nearly normal to the cover edge. The relation of 

 the first and second crops seems to be, that from the first supersaturated solution the first 

 crop crystals developed, until the solution was in equilibrium for that temperature; and 

 when the slides were placed in the cold a second crop developed gradually, probably 

 under increased pressure as the balsam seal of the slides hardened, until equilibrium had 

 been reached in the saturation of the solution for the lower temperature of about 10 or 

 less. Of course, on bringing the slides into the warmth of a heated room, this equilibrium 

 would be disturbed and resolution of the last-formed crystals would take place. As will 

 be seen from reference to the data in regard to the position of the elasticity axes, the 

 relative shortening of the crystal axes in the second-crop crystals is in the inverse order 

 of their elasticities; a, the axis of greatest elasticity, shortening more than b, the axis 

 of mean elasticity; while c, the axis of least elasticity, lengthens with respect to the 

 other two. 



The color of the crystals was the usual oxyhemoglobin red. Pleochroism is rather 

 strong ; a is pale yellowish-red ; 6 is a pale red, somewhat rose-pink ; c is deep blood-red. 

 Absorption is in order, c > 6 > a. Extinction is straight or symmetrical in all aspects. 

 The plane of the optic axes is the basal pinacoid and the orientation of the elasticity 

 axes is ab, b=c, c=a. On side views of the prism or on the vertical pinacoids traces 

 of an interference figure are seen in convergent light; on (010) the two brushes of the 

 biaxial figure are seen in the field, but they are widely separated. On (100) two brushes 

 show also, but pass out of the field in the diagonal position. The acute bisectrix is hence 

 evidently a, and the crystals are optically negative. This is indicated also by the pleo- 

 chroism, for b and c are much nearer together than & and a. 



DOKCAS GAZELLE, Gazella dorcas. Plate 39. 



This specimen was received from the Philadelphia Zoological Gardens. 

 The blood was clotted, but in good condition. The clot was ground in sand 

 with ether and the mixture centrif ugalized ; from the solution the slide 

 preparations were made in the usual manner. Crystals formed readily in 

 the dried protein ring, but were gradually dissolved as equilibrium was 

 established in the solution after covering; and then they reformed along 

 the cover edge, as they were dissolved from the protein ring, until the 

 solution in the slides was homogeneous. When the condition of equilib- 

 rium was reached in the solution, the crystals showed no sign of being 

 dissolved and were in good condition for days. The first crystals to form 

 are small rectangular plates, but with them are long rods; both seem to 

 be the same, however, and both are oxyhemoglobin, as determined by the 

 spectroscope. 



Oxyhemoglobin of Gazella dorcas. 



Orthorhombic : Axial ratio a : b : c =0.3639 : 1 : 0.4452. 



Forms observed: Brachypinacoid (010), base (001), unit prism (110), brachydome 

 (Oil), and, without measurement of angles, the macrodome (101) and the macropinacoid 

 (100). 



Angles: Prism angle 110 A HO =40 (normals) ; brachydome angle Oil A Oil = 48 

 (normals); outline of plates, 100 A 001=90. 



Habit tabular on (010), the plate bounded by the other two pinacoids (100) and 

 (001) when the crystals begin to grow (text figure 160) or by the combination of the 

 prism (110) and the brachydome (010) in the larger crystals (text figure 161). The 

 macropinacoid disappears as the crystals increase in size, but the base sometimes appears 

 to persist, although it is generally replaced by the brachydome. The crystals are usually 

 elongated along the vertical axis, so that on the brachypinacoid aspect the length is 



14 



