292 CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



soon become filled with a network of crystals, in which, besides the usual side views, 

 numerous cross-sections, mostly oblique, can be observed, and on these the macropina- 

 coid may be readily distinguished. The larger crystals frequently become covered over 

 with tufts and growths of smaller crystals, usually radiating more or less from certain 

 points along the larger crystals. Twinning seems to occur on the pyramid, both contact 

 and penetration twins. 



Pleochroism is marked; a pale rose-pink, b rose-pink, somewhat darker than a, 

 but rather pale; c deep rose-red. Double refraction is strong; extinction is straight in 

 all aspects. The orientation of the elasticity axes is a = a, b = 6, c=<5; the plane of the 

 optic axes is the brachypinacoid and the acute bisectrix appears to be the axis of least 

 elasticity, Bx a = c. The optical character is hence positive. 



DOMESTIC CAT, Felis domestica. Plates 88, 89, and 90. 



The animal was killed in the laboratory and bled into oxalate. Several 

 preparations were made from different specimens. Whole blood, ether- 

 laked and centrifugalized, was mounted as slide preparations and was 

 found to crystallize very slowly; but quite good crystals of reduced hemo- 

 globin formed 30 hours after the preparations were made. The habit of 

 these crystals is different from those prepared by the other methods de- 

 scribed, but the forms, and the angles of the corresponding forms are the 

 same. Several preparations were made from corpuscles settled from the 

 plasma, both of the simply ether-laked corpuscles, and of the ether-laked 

 corpuscles diluted with an equal volume of water. These all gave satis- 

 factory preparations that crystallized very readily. Laking by repeated 

 freezing and thawing, instead of laking with ether, gave perhaps the best 

 crystals; but all of the preparations made from the corpuscles alone gave 

 good results. The solution was of the color of oxyhemoglobin, and the first 

 crystals to appear were minute needles that seemed to be oxyhemoglobin. 

 Almost at the same time, irregular groups of crystals, which were evidently 

 reduced hemoglobin, began to form; and these were the first crystals to 

 attain any considerable size and definite shape. Prismatic crystals of a 

 purplish color, but apparently showing the absorption spectrum of oxy- 

 hemoglobin, appeared soon after the crystals of undoubtedly reduced hemo- 

 globin. All seemed to have the same axial ratio. The spectroscopic exami- 

 nation was interfered with by the oxyhemoglobin solution, so that the 

 oxyhemoglobin lines might have come from the solution. The crystals that 

 appeared to be oxyhemoglobin were not at all of the same color as the 

 undoubtedly oxyhemoglobin crystals of other cats, nor did they show the 

 forms usual in such crystals in the cats. They will all be described as 

 reduced hemoglobin, provisionally. 



Reduced Hemoglobin of Felis domestica. 



Orthorhombic: Axial ratio a : b : 6 =0.9656 : 1 : 0.3839. 



Forms observed: Unit prism (110), brachydome (Oil), brachypinacoid (010), 

 macroprism (320), macrodome (301), macropinacoid (100). 



Angles: Prism angle 110 A 1TO=88; macroprism angle 320 A 320=65 30'; 

 brachydome angle Oil A Oil =42; macrodome angle 301 A 301=100, all normals. 



Habit different in the different types of crystals, but in general prismatic. The 

 first crystals to appear are long needles, so thin that their forms can not be determined 



