190 CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE UNGULATES. 



monoclinic crystals are (with the one exception above noted) all optically 

 positive, while the orthorhombic and tetragonal crystals are all optically 

 negative. In the case of some species of the ungulates of which we had 

 ample supplies of blood, such for instance as the horse and mule, several 

 kinds of oxyhemoglobin were observed; the same was seen in one of the 

 antelopes, and in these cases the optical characters followed the above 

 rule, and changed in the same species with the crystal system. In most of 

 the species, however, but one form of oxyhemoglobin was noted. 



Reduced-hemoglobin crystals were recorded in several cases, and 

 sometimes they crystallized in the same system as the oxyhemoglobin, but 

 in other cases they did not. Thus in the chevrotain, the common sheep 

 and the blue sheep of Thibet, the oxyhemoglobin crystallizes in the mono- 

 clinic system, in each species, and the reduced hemoglobin in the orthorhom- 

 bic system. In every instance, when the oxyhemoglobin and the reduced 

 hemoglobin were observed in the same species, the two substances could 

 readily be distinguished by the form of the crystals, even though both 

 crystallized in the same system. 



UNGULATA. 

 HORSE, Equus caballus. Plates 24 to 26. 



Horse blood was obtained from the Veterinary Department of the 

 University of Pennsylvania when needed, being from horses undergoing 

 operations, etc. It was received in fresh condition and was prepared in 

 various ways, the whole blood or the centrifugalized corpuscles being 

 used. Experiments were made on this blood to test the influence on the 

 crystals of various salts and substitutes for plasma, etc., and it has been 

 probably more thoroughly studied in this research than the blood of any 

 other species, except the mule. The usual method of preparing the blood 

 by oxalating, laking with ether, and centrifugalizing gives in the fresh 

 blood the monoclinic plates that are characteristic of horse blood, but the 

 first crystals to form in this case are orthorhombic prisms ; these, however, 

 are rapidly dissolved as the monoclinic plates develop. When the oxalate 

 is omitted the orthorhombic prisms are more permanent, and sometimes 

 remain the principal crystals in the slide, but the monoclinic plates also 

 appear with no difference in habit or form from those which develop in the 

 oxalated blood. Carbon-monoxide hemoglobin was made by displacing 

 the oxygen in oxyhemoglobin by the carbon monoxide of illuminating 

 gas (water-gas) and this was crystallized under various conditions and 

 compared with the oxyhemoglobin crystals. In both oxyhemoglobin and 

 CO-hemoglobin two forms of crystals were observed, showing that both 

 oxyhemoglobin and CO-hemoglobin are dimorphous. These varieties are 

 distinguished as a-oxy hemoglobin, /3-oxyhemoglobin, etc. 



a-Oxy hemoglobin of Equus caballus. 



Orthorhombic: Axial ratio a : b : 6 =0.7467 : 1 : 0.4097. 

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



Angles: Prism angle 110 A 1TO=73 30' (normals); macrodome angle 101 A 

 TO 1=57 30' (normals). 



