156 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



These methemoglobin crystals were found in blood of shad that had died in the 

 air, and in freshly drawn blood that had been exposed to the air, and seem to be due to 

 a separation of the metoxyhemoglobin into methemoglobin and oxyhemoglobin, which 

 latter may be afterwards changed to reduced hemoglobin before the methemoglobin 

 disappears. The formation of the pure methemoglobin, which crystallizes in these hex- 

 agonal plates, is probably due to the further oxidation. 



CARP, Cyprinus carpio. Plates 5 and 6. 



Blood of the carp was obtained from live fish caught at Gloucester, New 

 Jersey. It was oxalated, ether-laked, and slides prepared within a few hours 

 after it was collected. The blood had a brownish color, and was probably 

 the metoxyhemoglobin mixture. After standing in a test-tube for 24 hours 

 it was practically all converted into reduced hemoglobin. Preparations of 

 this were also made and examined. Both the metoxyhemoglobin and the 

 reduced hemoglobin crystallized readily, but without any separation of 

 pure methemoglobin. They are isomorphous, having apparently almost 

 the same axial ratio, and perhaps the axial ratios are actually identical. 



(1) Metoxyhemoglobin of Cyprinus carpio. 



Orthorhombic: Axial ratio, a : b : c= 0.949 : 1 : 1.03. 



Forms observed: Prism (110), base (001), and, from twins on the macrodomes, 

 also macrodomes (301), (201), (302). 



Angles: 110 A 110= 93 (87 normals). 110 A 001 =90; from twins 302-302 = 

 68 30'; 201 A 201=55 15'; 301 A 301 =37 30'. 



Habit generally tabular, nearly square plates, formed by flattening on the base (001) 

 in combination with the prism (110) (text figures 16 and 17); also long prismatic, formed 



by development of the prism in the 

 same combination (text figure 1 8) . The 

 prismatic crystals are the first to ap- 

 pear; these are gradually absorbed as 

 the plates develop. Twins are common 

 in the prismatic habit, apparently on 

 the macrodomes noted above; they are 

 not so common in the tabular habit, 

 but apparently the twin on (302) oc- 

 curs. Parallel growths are common in 

 the tabular form; perhaps also homo- 

 geneous regular growths occur. This 

 parallel growth produces a piling up 

 of the plates, and composite crystals 

 and groups result. 



Pleochroism is marked ; the colors 

 1 are shades of brownish-red. Orienta- 

 ls. 10. 17, 18. Cyprinu, carpio Metoxyhemoglobin. tiOD f *** elasticity axes Was made 

 Fio. 19. Cyprinta carpio Reduced Hemoglobin. Out US follows: fl=0, D=a, C=C. The 



interference figure was not observed. 



Extinction is symmetrical on the plates when examined on the base (001) and straight 

 when examined on edge. 



(2) Reduced Hemoglobin of Cyprimis carpio. 



Orthorhombic : Axial ratio, a : b : c =0.949 : 1 : 1.098. 



Forms observed: Prism (110), base (001), macrodome (401). 



Angles: 110 A 110=93 (87 normals); 110 A 001 =90; 401 A 501=27. 



17 



b- 



