CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE RODENTIA. 243 



^-Oxy hemoglobin of Hydrochcerus capyvara. 



Orthorhombic : Axial ratio not determinable. 



Forms: Unit prism (110)? terminations were wanting. 



Angles: No angles could be measured. 



Habit prismatic, the crystals appear to be a prism, much elongated; but perhaps 

 the planes may be two pinacoids. When examined, a few hours after the crystals had 

 begun to form, the terminations were imperfect and not measurable. Later they were 

 lost by resolution. 



Pleochroism was weak; c deep red, a (or b) somewhat paler. 



Extinction is parallel to the length of the crystal in all aspects that were examined. 

 On the side view, in some cases, a biaxial figure was seen, with the plane of the optic 

 axes including the vertical axis, which is evidently c; this must, therefore, have been 

 seen when looking along a and the optical character is negative, as in the case of the 

 tetragonal crystals of a-oxyhemoglobin. The crystallization is evidently orthorhombic, 

 but the crystallographic constants can not be determined beyond those already stated. 



DOMESTIC RABBIT, Lepus cuniculus. Plates 59-61. 



The living animal was purchased and bled into oxalate in the labora- 

 tory. The corpuscles were separated from the plasma by centrifugalizing; 

 and the preparations were made from the corpuscles by laking with ether 

 and centrifugalizing for 3 hours. The slide preparations were made from 

 the clear centrifugalized blood as usual. Crystallization begins in the 

 protein ring soon after the slides are covered, and it proceeds rapidly at 

 room temperature. As the solution under the cover comes to an equilib- 

 rium, these first crystals dissolve and disappear from the slides. Upon 

 putting the slides in the cold at near C. a second crop of crystals appears, 

 some of which are like the first crop and some are of a different type. These 

 are distinguished as a-oxyhemoglobin and /2-oxyhemoglobin. The a-crystals 

 are less soluble and may be examined at near room temperature; but the 

 /3-crystals are much more soluble, and dissolve rapidly when the tempera- 

 ture is raised a few degrees above C. They had to be examined and 

 photographed in a room temperature near the freezing-point. Another 

 preparation, made from the same blood, was evidently not evaporated quite 

 to the same point as the first before applying the cover; for, while two 

 types of crystals developed, both tended to dissolve upon increasing the 

 temperature a few degrees above C., and they therefore had to be exam- 

 ined at about this temperature. So long as the preparations were kept at 

 about the freezing-point the crystals continued in excellent condition. 



a-Oxyhemoglobin of Lepus cuniculus. 



Monoclinic: Axial ratio a : b : c =0.643 : 1 : 0.797; /? = 85. 



Forms observed: Unit prism (110), clinoprism (320), clinodome (Oil), clinopina- 

 coid (010), orthopinacoid (100). 



Angles: Unit prism 110 A 1TO=65 30' (normals); clinoprism 320 A 320=88 

 (normals); clinodome Oil A Oil =77; prism edge to dome edge, in the plane of sym- 

 metry = 85 (normals) =/?, or 95 actual angle. 



Two habits of crystals develop: (a) the first crystals to appear are usually pris- 

 matic, consisting of the two pinacoids and the clinodome, elongated vertically and flat- 

 tened on (100) (text figure 247), and with or without the unit prism (110) (text figure 

 248) ; (b) the second type, which is much more symmetrically developed, consists of 

 the clinoprism (320) in combination with the clinodome and the clinopinacoid (text 

 figure 249). Type (a) crystals are elongated vertically and striated on the orthopinacoid; 



