158 CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



Habit prismatic, long or short prisms, terminated by one or both domes, the habit 

 varying with the method of preparation. In crystals prepared by defibrinating and 

 ether-laking without addition of oxalate the crystals are very long prismatic, 20 to 30 

 times as long as they are thick (text figure 20) ; those prepared with an excess of oxalate 

 are very short prismatic, nearly equidimensional (text figure 21); when the normal 

 amount of oxalate is used the crystals are intermediate in form, the ratio of thickness 

 to length being about 5 : 1 (text figure 22). Twins are common, cross-shaped, as in 

 staurolite, one on the brachydome (Oil) making a square cross (text figure 23), and one 

 on the pyramid (111) making an oblique cross (text figure 24), being the usual forms. 

 A twin on what appears to be (032) was also observed, and another on (043) ; these 

 were somewhat doubtful. No cleavage was observed, but the crystals are brittle. 



Pleochroism is very weak, the colors much more brownish than is usual with oxy- 

 hemoglobin, but with the spectroscope the double absorption band of oxyhemoglobin 

 is shown in most specimens; in one case, when excess of oxalate was used, but one faint 

 dusky band appeared at 590 /yt to 570 fi/jt. The colors are pale brownish-red; c and 6 

 are nearly equal and darker than a. Orientation of the elasticity axes is a =a, b = b, c=6. 

 The plane of the optic axes is the brachypinacoid, and the interference figure appears 

 when looking along a, which is the acute bisectrix. Hence, the optical character is nega- 

 tive. But b and c are nearly equal, and in some cases a figure was seen with c =b and b =6, 

 the basal pinacoid being the plane of the optic axes. The axial ratio shows the crystal 

 axes 6 and 6 equal. Pleochroism is hence scarcely noticeable when looking along a, but 

 becomes distinct when looking along b. The axial angle is about 2=35, the figure 

 being rather dusky. 



Reduced Hemoglobin of Necturus maculatus. 



The crystals of reduced hemoglobin were detected in only one preparation. These 

 gave the spectrum of reduced hemoglobin distinctly. They were formed in a prepara- 

 tion in which oxalate was not used, and were mixed with crystals of oxyhemoglobin. 

 In form and angles, and in optical characters, they were not distinguished from the 

 crystals of oxyhemoglobin above described. They may have been paramorphous altera- 

 tions from the oxyhemoglobin crystals. 



REPTILIA. 



INDIAN PYTHON, Python molurus. Plates 7 and 8. 



Blood from two specimens was received, one from the Philadelphia 

 Zoological Gardens, and one from the National Zoological Park at Wash- 

 ington. The Philadelphia specimen was fresh blood, that from Washington 

 was received in a somewhat putrid condition. Both developed oxyhemo- 

 globin crystals; but in the specimen from Washington another type of 

 crystal developed besides the normal a-oxyhemoglobin crystal. The 

 Philadelphia specimen was prepared in two ways, (1) oxalated, ether-laked, 

 and centrifugalized; and (2) frozen, and after thawing centrifugalized. 

 The monoclinic crystals of habit (a) developed in both, and with a few of 

 the plates of habit (b) in both preparations. The specimen from Wash- 

 ington was in a firm clot, and this was broken up by rubbing with sand; 

 ether was added, and the blood diluted with a little neutral saline so that 

 it could be readily centrifugalized. The monoclinic crystals of habit (b) 

 developed in these slides; and in a few slides the tetragonal type of crystal 

 (/3-oxyhemoglobin) occurred rather plentifully. They developed after the 

 monoclinic crystals of a-oxyhemoglobin. 



