CRYSTALLOGRAPHY OF HEMOGLOBINS OF THE RODENTIA. 223 



uble and keep well at ordinary room temperature, showing no tendency to 

 dissolve, even in the rays of the electric arc lamp, when making the photo- 

 micrographs. They are the usual oxyhemoglobin red, and were determined 

 as oxyhemoglobin by the spectroscope. 



Oxyhemoglobin of Tamias striatus. 



Orthorhombic (?): Axial ratio about a : 6 : 6 =0.9246 : 1 : 0.589. 



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



Angles: Macrodome angle 101 A 101=65 (normals); brachydome angle Oil A 

 011=61 (normals); prism angle (calculated) 110 A 1TO=8530'. The prism angle 

 was not observed, but was calculated from the two dome angles which were measured, 

 but not very satisfactorily; hence the uncertainty as to the exact axial ratio. 



Habit prismatic on the vertical axis; the first prisms that develop are very long 

 and slender; later, stouter crystals form on which some measurements of the terminal 

 planes can be made. The common termination is the macrodome, one face much more 

 developed than the other, giving the crystal a very monoclinic aspect (text figure 190). 

 It may in fact be monoclinic, but the measurements of prism edge to macrodome seemed 

 to be symmetrical in the crystals examined, and extinction is straight in all aspects. 

 The prisms range in ratio of length to thickness from 15 : 1 to 100 : 1, and in most of 

 them the terminal macrodome is unsymmetrically developed. In some a brachydome 

 appears (text figure 191) and, some days after the slides were prepared, the two domes 

 were seen in equilibrium, in a few cases. The crystals grow in radiating tufts from the 

 protein ring and cover edge, and also scattered irregularly through the body of the slide; 

 but they do not appear to form twins. 



Pleochroism is rather pronounced; a pale yellowish-red, b pale rose-pink, c deep 

 red. The orientation of the elasticity axes is apparently a = a, b=b, c=i; but no inter- 

 ference figure was made out. As stated above, the extinction is straight in all aspects 

 of the crystals that could be examined. The optical character could not be determined, 

 but, from the pleochroism, it should be positive. 



PRAIRIE-DOG, Cynomys ludovicianus. Plate 48. 



Specimens of prairie-dogs were purchased from collectors in Ohio 

 and in Kansas City, and the animals were bled in the laboratory. Prep- 

 arations were made from the corpuscles, but not from the whole blood, 

 which probably prevented the characteristic plate-like crystals, common 

 in rodent blood, from developing. The corpuscles were oxalated, ether- 

 laked, and centrifugalized and from the clear solution the slide prepara- 

 tions were made as usual. Only one type of crystals developed and these 

 were not very favorable for observing the characters. They were oxy- 

 hemoglobin. 



Oxyhemoglobin of Cynomys ludovicianus. 



Probably orthorhombic: No axial ratio determinable. 



Forms observed: Evidently a unit prism, but the terminations were not perfect. 



Angles: No angles of the crystals could be measured. 



Habit of the crystals obtained was long prismatic, practically hair-like, and taper- 

 ing gradually to an acute point; but, in the larger crystals, a high power showed that 

 they were four-sided prisms, with a lozenge-shaped cross-section; and they probably 

 are orthorhombic, possibly tetragonal, but certainly not hexagonal. The polarization 

 characters showed that they must be one of these three systems. The needles grow in 

 tufts, radiating from a center, the adjacent tufts penetrating each other and forming 

 networks of interlacing fibers. 



