CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE UNGULATES. 193 



^ Pleochroism is strong; a pale yellowish-red, 6 rather bright red, c deep blood-red. 

 Extinction is symmetrical on the base, but oblique on the clinopinacoid sections, as well 

 as on all prism faces. The orientation of the elasticity axes is a A a = 13, in the obtuse 

 angle; 6=6; c A 6=5, in the obtuse angle; extinction on the clinopinacoid section 

 is hence 13 from the trace of the base, and 5 from the prism edge. The plane of the 

 optic axes is the clinopinacoid; and on the basal section one brush of the interference 

 figure is seen, somewhat out of the center of the field, revolving as the crystal is revolved. 

 The other brush is out of the field. The axial angle 2E is evidently more than 50, per- 

 haps about 60. The acute bisectrix is the axis of least elasticity Bx a = t, and the crystal 

 is optically positive. 



CARBON-MONOXIDE HEMOGLOBIN OF HORSE. 



The CO-hemoglobin was made by exposing the blood to illuminating 

 gas (water-gas) for several hours, and in laked bloods crystals form during 

 the time of exposure to the gas at the ordinary room temperature. The 

 solution, from which the crystals have been separated by centrifugalizing, 

 crystallizes very rapidly; too rapidly, in fact, when making slide prepara- 

 tions in the usual manner. In order to make the crystallization less rapid 

 the blood was diluted with a 50 per cent solution of egg-white and from 

 this the best crystals were obtained. As in the case of the oxyhemoglobin, 

 the addition of oxalate causes the development of the monoclinic crystal, 

 while in absence of oxalate mainly the orthorhombic crystals are formed; 

 but the addition of egg-white only retards the formation of the crystals, 

 and makes them finer in development, without in any way altering their 

 characters. The heat of the hand was found to be sufficient to dissolve the 

 crystals that had formed in the flask, during exposure to CO. To produce 

 the orthorhombic crystals, the laked blood, after exposure for some hours to 

 illuminating gas, was simply warmed by the hand, or by immersing the tube 

 in water at body temperature, and, after centrifugalizing a few minutes, the 

 preparations made. Only the orthorhombic crystals developed at first. The 

 best crystals were made by mixing one part of the CO-blood with one part 

 of egg-white, shaking with excess of ether and centrifugalizing a few minutes. 



By addition of oxalate to either the undiluted CO-blood, or the CO- 

 blood diluted with one part of a 50 per cent solution of egg-white, and 

 warmed in each case to body temperature, the monoclinic form only 

 developed. The crystals were of the same habit in preparations from the 

 undiluted blood and from the diluted blood. All of these CO-hemoglobin 

 preparations were made from fresh blood that had been ether-laked and 

 centrifugalized, so that it was clear before exposure to the water-gas. 

 There are hence two forms of the CO-hemoglobin, as was the case with the 

 oxyhemoglobin. These have been distinguished as a-CO-hemoglobin and 

 /^-CO-hemoglobin. 



a-CO-hemoglobin of Equus caballus. 



Orthorhombic: Axial ratio a : b : 6 = 0.7332 : 1 : 0.4106. 



Forms observed: Prism (110), macrodome (101). 



Angles: Prism angle 110 A HO =72 30' (normals) ; dome angle 101 A T01 =58 30' 

 (normals) . 



Habit long or short prismatic (text figures 114 and 115), prisms from 2 to 10 times 

 as long as they are thick, and terminated by the macrodome, with generally equal cle- 



13 



