244 



CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE RODENTIA. 



by the disappearance of this plane and the development of the clinoprism, while, at the 

 same time, the clinopinacoid becomes larger, they pass into the second type of crystals. 

 Type (b) crystals are tabular on the clinopinacoid, elongated vertically, and generally 

 smooth, not striated, as in the type (a) crystals. Both kinds of crystals of the a-oxyhemo- 

 globin are much smaller than the crystals of the ,3-oxyhemoglobin. The (b) type of 

 crystals form parallel growths and also seem to twin on the orthopinacoid; the twinning 

 was observed in polarized light. 



The color is the usual oxyhemoglobin red, but the crystals are quite pleochroic; a 

 colorless or pale yellowish; b rose-pink to pale red; c deep red. Double refraction is 

 moderately strong on most aspects; in all sections in the zone of 100-001 the extinction 

 is straight or symmetrical; on the plane of symmetry, looking along b, the extinction 

 is oblique; 15, in the obtuse angle, from the prism edge. On this aspect in some 

 crystals, a biaxial interference figure was seen with the above orientation, the plane of 

 the optic axes being inclined to the vertical axis 6 at 15. The orientation of the elas- 

 ticity axes is a A (5 = 15, in the obtuse angle; b A a = 10, in the acute angle; c=&. 

 The plane of the optic axes is hence normal to the plane of symmetry. The angle between 

 the optic axes was not accurately measured; the separation was considerable, however. 

 The acute bisectrix emerges normal to the plane of symmetry; it is c and hence the optical 

 character is positive. 



247 



N/ 



a/ 



248 



249 



251 



FIGS. 247,248,249. Ltput cuniculus a-Oxs-hemoglobin. FIGS. 250,251. Lepui cuniculue B-Oxyhemoglobin. 



^-Oxyhemoglobin of Lepus cuniculus. 



Orthorhombic : Axial ratio a : b : c =0.5317 : 1 : c. 



Forms observed: Unit prism (110), base (001). 



Angles: Unit prism angle 110 A 110=56 (normals); prism to base 110 A 001 = 

 90. Many oblique sections of the prism in the position of a brachydome were produced 

 by the slide and cover; these had the angle of the prism (210), but were oblique sections, 

 as could be shown by their optical properties. This angle of the prism (210) is 30. 



Habit tabular on the base; or, in case of the crystals that were interfered with 

 by the slide and cover, flattened on a brachydome. The tabular crystal consists of the 

 very short prism cut by the base, and in some cases traces of a macroclome were seen 

 (text figures 250 and 251). These crystals are many times the size of those of the a-oxy- 

 hemoglobin. The oblique sections of the crystals are particularly common, but they 

 are not always at the same angle, nor in the zone of the brachydomes. Their angle 

 generally runs near 30. These /^-crystals are much more soluble than the a-crystals 

 as a rule, and they are corroded so rapidly that, in spite of the fact that they were photo- 

 graphed at a room temperature of about C., they show the effect of solution in etching 

 figures, which appear on their surfaces in many of the photographs. 



The crystals were somewhat more of a scarlet-red color than the a-crystals, but 

 the absorption spectrum was the same, that of oxyhemoglobin. The difference in color 

 is due to the difference in the pleochroic colors. The pleochroism is a pale yellow-red 

 to nearly colorless; b pale scarlet-red; c deep red. The orientation of the elasticity 

 axes is 0=6, b=o, C = <J. The macropinacoid is the plane of the optic axes and the acute 

 bisectrix Bx a =c. The optical character is hence positive. In the crystals presenting 

 the basal aspect, the symmetrical interference figure is seen, in convergent light, with 



