. Carnegie Institution of Washington publication. . (.7 FIGS. 66, 67. Dutelphit mrginiana Reduced Hemoglobin. FIGS. 68. 69. D. virginiana a-Carbon-monoxide Hemoglobin. Habit, rhombic plates with oblique sides, composed of base and prism, the crystals generally very perfect and sharp (text figures 66 and 67). They usually occur singly, but also twin with the normal to the base as the plane of twinning and the twin axis normal to the prism-base edge, the composition face being the basal pinacoid. This type of twin, " horse-type," is seen in a-oxyhemoglobin (text figure 51) and is the c
. Carnegie Institution of Washington publication. . (.7 FIGS. 66, 67. Dutelphit mrginiana Reduced Hemoglobin. FIGS. 68. 69. D. virginiana a-Carbon-monoxide Hemoglobin. Habit, rhombic plates with oblique sides, composed of base and prism, the crystals generally very perfect and sharp (text figures 66 and 67). They usually occur singly, but also twin with the normal to the base as the plane of twinning and the twin axis normal to the prism-base edge, the composition face being the basal pinacoid. This type of twin, " horse-type," is seen in a-oxyhemoglobin (text figure 51) and is the common twin on the base in all of these monoclinic reduced hemoglobins and oxyhemoglobins, especially when the prism angle is near 60°. These twins are often complex and the polysynthetic arrangement is very common. The crystals are readily distinguished from the a-oxyhemoglobin by their color, and by the fact that they occur singly and not in parallel growth, as is so commonly the case in the a-oxyhemoglobin. In the photographs they appear as lighter-colored, more transparent crystals than the oxyhemoglobin crystals. Pleochroism is very strong; a very pale violet, nearly colorless; b deep reddish; c deep claret-color to purple. Ex- tinction is symmetrical or nearly so on the flat basal face; on edge looking along the axis 6 it is oblique; the extinction angle is a A a = 13°, in the obtuse angle. The orientation of the elasticity axes is as follows: The axial plane is the plane of symmetry; a A a = 13° in the obtuse angle, b = 6, c A <! = 11° in the obtuse angle. On the base, the interference figure is readily observed, with the two brushes showing, but in somewhat unsymmetrical arrangement, due to the angle of 13° between a and a; the brushes are widely separated. The acute bisectrix is hence Bxa = c, and the optical character is positive. 12. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - col
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