CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE UNGULATES. 



191 



105 



106 



Habit, at first, long hair-like crystals, which soon become more or less stout prisms; 

 consisting of the unit prism terminated by the macrodome (text figures 105 and 106) ; 

 the relative development of the two forms depending upon the method of preparation, 

 and ranging from a prism with a length double the thickness (text figure 106) to one with 

 the length ten times the thickness or more (text figure 105). They grow at first in the 

 dried plasma ring, almost as soon as the cover is put on the drop, and develop very 

 rapidly, these being the long hair-like crystals that are afterwards dissolved. But they 

 also develop throughout the slide in shorter, doubly terminated crystals. The rods 

 in the protein ring begin to form within 3 or 4 minutes after placing the blood on the 

 slide, and even before the cover is applied in case of blood containing oxalate; in such 

 a blood with oxalate, the monoclinic tabular crystals of /?-oxyhemoglobin appear within 10 

 minutes after placing the drop of blood on the slide. But to obtain good orthorhombic 

 crystals of a-oxyhemoglobin without 

 the /?-oxyhemoglobin the oxalate is 

 omitted, and the preparation made 

 as follows: The blood is defibrinated 

 by beating and then centrifugalized 

 to collect the corpuscles; these are 

 separated by draining off the serum 

 and then laked with ether, excess 

 of ether being added to dilute the 

 thickened blood until it will centri- 

 fugalizc readily. This can be done 

 rapidly, with the excess of ether, and 

 in a few minutes the blood is clear 

 enough to mount. The drops are 

 placed on the slides and allowed to 

 evaporate until large crystals begin 

 to form, when the cover is applied. 



Such preparations rarely show the /?-oxyhemoglobin plates before about 24 hours or 

 more after the preparations are made, but the a-oxyhemoglobin crystals are very large 

 and fine. As the /?-oxyhemoglobin forms sparingly in these slides, the a-oxyhemoglobin 

 crystals are quite permanent and show no tendency to dissolve. These a-oxyhemoglobin 

 crystals generally grow singly or in tufts and parallel groupings from the protein ring 

 or from the cover edge; they usually occur singly through the body of the slide, and twin 

 only rarely. What seem to be twins on a unit pyramid were observed (text figure 107). 



Pleochroism is quite marked; a pale yellowish-red to flesh-pink, b rose-red, c deep 

 blood-red. The extinction is straight in all aspects. The orientation of the elasticity 

 axes is a=(5; 6=6; c=a. The plane of the optic axes is the brachypinacoid; and on 

 basal sections, looking along 6 in convergent light the biaxial figure is seen with the 

 brushes well separated; the angle between the axes measured in white light (practically 

 for red, owing to the color of the crystals) 2E = about 45. The acute bisectrix is 

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



fl-Oxyhemoglobin of Equus caballus. 



Monoclinic: Axial ratio a : b : i =1.600 : 1 : 6; /? = 72 for untwinned crystals; 

 in those that are twinned the angles change slightly and the ratio is a : b : 6 =1.6976 : 

 1 : i, with the same angle for /?. 



Forms observed: Unit prism (110), base (001), orthopinacoid (100). 



Angles: Prism angle, traces of the prism on the base, edges 110-001 A 110-001=64 

 in untwinned crystals, but usually about 61 as the crystals are generally twinned; 

 prism edge to base, edge 110-lTO A 001 =72 = = 100 A 001. 



Habit, in lozenge-shaped tables, tabular on the base (text figures 10S and 109), 

 the crystal being the oblique section of the prism made by the basal pinacoid, and the 

 ratio of the length of the prism to the length of the symmetry axis varying from 1 : 1 to 



FIGS. 105, 106, 107. Equus caballui n-Oxyhemoglobin. 



