318 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



cold, apparently at the expense of the granular oxyhemoglobin that had 

 separated; the first crystals to appear were rather imperfectly formed, but 

 later well-shaped plates were observed. The general type of crystals is 

 that of the a-oxyhemoglobin, as seen in the genus Papio. 



In another experiment on human blood a few imperfect crystals of 

 oxyhemoglobin were obtained that agreed well in type with the y-oxyhemo- 

 globin crystals of the genus Papio. Crystals of reduced hemoglobin are 

 readily obtained in human blood, and have been described, more or less 

 exactly, by a number of observers. 



a-Oxyhemoglobin of Homo sapiens africanus. 



Orthorhombic : Axial ratio not determinable from the faces that are developed. 

 Forms: Macropinacoid (100), brachypinacoid (010). base (001). 

 Angles: All angles between edges or between planes are 90. 



403 



b-" 



409 



b- 

 a 



410 



Flos. 408, 409. Hvmu sapiens africanus a-Oxyhemoglobin. FIGS. 410 411. Homo sapiens africanus Reduced hemoglobin 



Habit, at first long lath-shaped (text figure 40S) ; growing singly or in more or less 

 closely aggregated bundles, with the large faces in contact; the smaller crystals are 

 shreddy, with imperfect ends; and the ends are sometimes rounded as though due to 

 erosion. Later larger and broader plates develop, which are quite well formed (text 

 figure 409). These also showed the tendency to pile up on the large face (100); and on 

 edge views, looking along b for instance, the lamination is quite marked. No planes except 

 the pinacoids were developed, which is the rule in Papio also. Xo twins were observed. 



The crystals are so thin that pleochroism is not noticeable, but the double refraction 

 is fairly strong, and the relative elasticities can readily be observed. Extinction is straight 

 in all aspects. The orientation of the elasticity axes is a =b; b=a; c=<*. The elasticity 

 of b and c is nearly the same; hence the acute bisectrix is probably the axis of greatest 

 elasticity, Bx a = a, and the optical character is positive. In convergent light, on the 

 macropinacoid, or looking along b, no trace of the interference figure was seen; this 

 was the only aspect in which the convergent light could be used. 



In another experiment, in which the preparation was made from cor- 

 puscles washed with neutral saline and separated by centrifugalizing, then 

 laked with ether, etherized and centrifugalized again, and the covers not 

 sealed with balsam, crystals of oxyhemoglobin developed after two days in 

 the cold, at a temperature of C. These crystals were long, acicular, 

 tapering to a sharp point at the ends, and they occurred in parallel and 

 radiating groups. They polarize light and extinguish straight, showing 

 greater elasticity normal to the length. In some cases the groups of crystals 

 or the imperfect crystals showed a form that closely resembled elongated 

 rhombic plates, very much like the y-oxyhemoglobin crystals of the genus 

 Papio. The angle of the plates was about 28, but they were very imper- 



