260 CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF THE 



The first-formed crystals do not attain large size, and are gradually dissolved into 

 the solution, as larger crystals of a second crop (text figure 285) begin to appear along 

 the cover edge. These latter do not appear to twin as do those of the first crop; they 

 grow singly, or united into irregular aggregates, or forming larger groups in parallel 

 growth. As they attain a large size, they develop many false planes due to the interfer- 

 ence of the cover and slide with the growth of the crystals; and in many cases such false 

 planes are symmetrical with the principal axis. In these crystals the form (010), the 

 clinopinacoid, is sometimes observed, appearing on the end of the binary axis that is 

 cut by the unit pyramid (Til) (text figure 285). The hemimorphic character of these 

 crystals is very noticeable; not only in the perfect crystals, but also in sections, which 

 show at the one end the unit pyramid and at the other the unit prism, and these sections 

 appear to be most commonly in the zone of the normal to the prism-base edge. 



The color of the crystals is the usual oxyhemoglobin scarlet, and pleochroism is 

 quite marked; fl is colorless or nearly so; b is almost equal to c, and both are deep scarlet- 

 red. A few sections were seen, evidently in the zone of 100 A 001, but showing the 

 hemimorphic character very markedly, that gave straight extinction, because such a 

 section is parallel to the binary axis. All other sections of the plate gave oblique extinc- 

 tion, the maximum extinction angle being reached on the clinopinacoid section, and 

 giving about 19, measured from a. The usual cross-sections of the tabular crystals 

 are normal to the edge Tl 1-001 or nearly so and give an extinction angle of 12 to 13, 

 about. On the base, the extinction is symmetrical with the outline of the crystal. The 

 biaxial interference figure is indicated by one brush of the figure appearing on the base 

 in convergent light, with traces of the second brush on revolution of the crystal. The 

 orientation of the elasticity axes is c A a =19 (about), in the obtuse angle; a A (i = 6 

 (about), in the obtuse angle; b=fr. The plane of the optic axes is the clinopinacoid, 

 and the acute bisectrix of the axes is the axis of greatest elasticity, Bx a = a. The optical 

 character is hence negative. The angle IE could not be measured, but was apparently 

 not very large, perhaps about 60. 



Metoxy hemoglobin of Ursus americanus. 



Monoclinic hemimorphic (monoclinic sphenoidal), like the oxyhemoglobin, and 

 the angles about the same. One or two gave an angle of the plate of 80, but most of 

 them ran about 78 30', as in the oxyhemoglobin. The habit of twinning and the forms 

 observed were the same; the optical characters are identical in the metoxyhemoglobin 

 and in the oxyhemoglobin; the extinction angles, the negative character of the double 

 refraction, and the relative elasticities could not be distinguished in the two. The 

 crystals which developed in slides that had been kept for a considerable time were 

 probably paramorphous. The thin crystals showed the oxyhemoglobin bands only, 

 but the thicker crystals showed the characteristic band in the red and the shortening 

 of the blue end of the spectrum characteristic of metoxyhemoglobin. 



POLAR BEAR, Ursus maritimus. Plate 70. 



The specimen was received from the National Zoological Park at 

 Washington, District of Columbia, and was the blood from a young bear 

 that had died in the Park. The blood was quite thick and slightly putrid. 

 It was oxalated, laked with ether, and centrifugalized, and from the clear 

 solution thus obtained the slide preparations were made. Crystals began 

 to form in the protein ring at room temperature, and the blood crystallized 

 readily; but as the solution came to equilibrium in about 1 hour these first- 

 formed crystals were partly dissolved, and a second crop began to form 

 along the cover edge. The first crop was almost entirely dissolved in the 

 solution, but the second crop of crystals was more permanent. As in the 



