284 CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



but these crystals are much thicker than those of type (a) and do not pile up to the same 

 extent. They are not very plentiful, not nearly so much so as those of the first type. 

 Actual twins of either of these types were not observed. As no forms are found in the 

 one type that occur in the other, the correlation of the two rests upon the correspondence 

 of the optical characters, and the orientation of the elasticity axes is assumed to be the 

 same in each type. On this basis, the complete axial ratio is made out; t being deter- 

 mined from type (a) and a from type (b). 



Pleochroism is marked in type (a) crystals, but not very noticeable in type (b) 

 when each is examined on the large face. This of course depends upon which of the 

 elasticity axes lie in the plane of this large face, in each case. When all edge views are 

 considered, as well as the flat views, the pleochroism is the same in both types. Crystals 

 of type (a) are rather pale in ordinary light, and with one nicol prism they appear either 

 deeply colored or nearly colorless; the crystals of type (b), on the other hand, when 

 viewed on the flat, are deep scarlet in ordinary light; and with one nicol are much the 

 same color, owing to the two elasticity axes in this plane (001) being nearly of the same 

 elasticity. Pleochroism is: a nearly colorless to pale pinkish, 6 rather deep scarlet-red, 

 c deep red; the colors of b and c are nearly equal. Extinction is straight in all aspects, 

 and in both types of crystals. In type (a) crystals the interference figure is difficult 

 to observe, on account of the position of the acute bisectrix; and it was only made out 

 in exceptional cases, when the crystals were in a proper position for observation. But 

 in type (b) the figure is easily seen, as the acute bisectrix is normal to the large plane 

 of the plate. The orientation of the elasticity axes is a = c, 6 =a, c =6. The plane of the 

 optic axes is the macropinacoid, and the acute bisectrix is the vertical axis, Bx a = a. 

 The optical character is therefore negative. This is, of course, true of both types of crys- 

 tals, and it is one of the reasons for identifying them as the same substance. The biaxial 

 figure is easily observed in the type (b) crystals and is seen on the base; the brushes do 

 not open very widely and the axial angle 2E =25. In some slides in which the type (b) 

 crystals appeared, there were seen long needle-like crystals of oxyhemoglobin, which 

 showed the characters of these type (b) crystals on edge. They are probably the same 

 crystals, with the development prismatic on the two pinacoids (100) and (010), and 

 elongated along the vertical axis. 



Metoxyhemoglobin of Felis leo. 



The crystals of oxyhemoglobin passed by paramorphous change into brownish 

 crystals, giving the spectrum of metoxyhemoglobin, but without any alteration in the 

 angles or change in the optical characters. 



Reduced Hemoglobin of Felis leo. 



Orthorhombic : Axial ratio a : b : t =0.9742 : 1 : 0.3707. 



Forms observed: Unit prism (110), macrodome (101). 



Angles: Prism angle 110 A 1TO=8830' (normals); macrodome angle 101 A T01 = 

 41 50' (normals). 



Habit prismatic; the normal crystals consisting of the unit prism and macrodome, 

 elongated on the prism and with the ratio of length to thickness very variable; about 

 5 : 1 is an average (text figure 321). Some crystals are enormously elongated and even 

 needle-like, others are abnormally short until the above ratio becomes 2 : 3. The crys- 

 tals become, in some cases, relatively enormous, and, under the cover, are often more 

 than 2 mm. long by more than 0.5 mm. thick. The needles also attain a length of 2 mm. 

 and more, but remain very thin. As in the cats generally, preparations of the whole 

 blood of the lion, fresh and not exposed to the air, first develop crystals of reduced hemo- 

 globin and then later crystals of oxyhemoglobin, even when the spectrum of the blood 

 does not show reduced hemoglobin at all. Therefore, in both of the specimens of blood 

 examined, crystals of reduced hemoglobin were the first to appear and were very plenti- 

 ful. The shorter crystals with a ratio of length to thickness of 5 : 1 to 3 : 1 appeared 

 first; later, along with the crystals of oxyhemoglobin, and especially when these began 



