CRYSTALLOGRAPHY OF HEMOGLOBINS OP THE RODENTIA. 225 



respectively. The rods are possibly a form of the y-oxyhemoglobin with 

 prismatic development, but they appear to be orthorhombic, and will be 

 called /3-oxyhemoglobin. The other forms observed, which are reduced 

 hemoglobin and metoxyhemoglobin, were simply paramorphous alterations 

 of the normal crystals. They appeared mainly in the a-oxyhemoglobin 

 form, and only in slides that had been kept for some days. 



a-Oxy hemoglobin of Marmola monax. ^^- v 



Hexagonal or pseudohexagonal: Axial ratio not deter- \J" - - 1 --- " ^J 

 minable, as no pyramidal forms were observed. > ---- ?92 



Forms observed: Unit prism (10TO), base (0001). FlG - 192 - ^ a '\ J? onax a ' xy 



Angles: Prism angle 60; prism to base 90. 



Habit thin tabular; in the whole blood preparations, the first crystals to appear 

 are very minute hexagonal plates in the protein ring; these are later dissolved with 

 development of the needles of /?-oxyhemoglobin. In diluted blood, the typical a-oxy- 

 hemoglobin plates are developed; they are large, well-formed, and very regular hexagonal 

 plates (text figure 192), occurring singly or in complicated groups in parallel growth 

 orientation, either piled on the base (plate 49, figs. 290, 291, and 292) or in arborescent 

 forms (plate 50, fig. 297) ; also in partial orientation, which looks complete on the base, 

 but is seen to be partial in edge view, the plates radiating from the center of the main 

 groups as though twinned in the zone of two opposite unit-pyramid faces (plate 59, 

 figs. 295 and 296) . Interference with the slide and cover produces in these groups on edge 

 broad lath-shaped individuals which look rather orthorhombic. Often a single large plate 

 may have on its basal surface several small concentric groups, all in perfect parallel 

 growth orientation with the main large crystal. Twins are on the unit pyramid, but 

 owing to the tendency to produce radiating groups the angle of the pyramid could not 

 be determined with any certainty. 



The color of the plates varies with the thickness, but they show rather strong pleo- 

 chroism; u> deep red, e pale reddish to colorless. On the base, the crystal is singly refract- 

 ing; on edge, the double refraction is quite strong, and the extinction is straight parallel 

 to the base. In convergent light, a dusky cross appears on the basal aspect, showing 

 the uniaxial character. The vertical axis is the direction of greater elasticity, cu > s, 

 and the optical character is negative. 



[3-Oxyhemoglobin of Marmota monax. 



Orthorhombic or monoclinic: No axial ratio is determinable. 



Forms observed: Apparently two vertical pinacoids and a terminal dome or some- 

 times one plane of such a dome. 



Angles: The crystals were not perfect enough to measure angles with exactness; 

 the angle of the terminal dome seemed to be about 58 (normals), and the two pinacoids 

 at right angles. 



Habit ordinarily hair-like, the ends tapering to a point, without any definite plane 

 terminations; some larger crystals were lath-shaped and showed the dome or oblique 

 termination described above (text figure 193). The crystals grew in tufts, radiating 

 slightly; or in groups of such tufts, sometimes radiating from a center like the spokes 

 of a wheel; along the protein ring they shoot out normal to the surface and form a con- 

 tinuous mass of hairs on the inside of the ring; outside of it the crystals are larger and 

 longer and the tufts more dense. The crystals are quite elastic, bending considerably 

 before they break. They reach a large size, the individual tufts of hairs being easily 

 seen with the unaided eye. 



When the crystals are lath-shaped, the flat surface of the lath is usually presented; 

 and on this surface the pleochroism is quite marked. The length of the lath is apparently 

 c, the width b, and the thickness a. On this aspect above described the axes b and c 



15 



