266 CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



ratio was not always obtained ; but, as noted above, the dome angle, giving 

 the ratio of a : 6, was made out in each case. It is very constant in the 

 entire group, as will be seen from table 44, page 279 ; and the common dog 

 and the chow dog, domesticated varieties, include the extremes of varia- 

 tion noted in this ratio. Different strains of the common dog vary among 

 themselves in such a way as to lead to the conclusion that they are a poly- 

 phyletic group; some individuals seem to approach the wolf, others the 

 jackal, etc. But this part of the subject has not been worked out with 

 sufficient detail to warrant any final conclusions. In all cases but one the 

 material examined was oxyhemoglobin ; and as the material in this one 

 case was metoxyhemoglobin, into which the oxyhemoglobin was in several 

 other cases seen to pass by paramorphous change, it may safely be said 

 that all of the crystals examined were strictly comparable. It is well known 

 that crosses between the dogs are readily obtained; and, from the close 

 resemblance of the crystals in the species examined, it would seem probable 

 that any one of these species could cross with any other. 



CANIDJB. 



DOG, Cants familiaris. Plate 72. 



Specimens of dog blood were obtained from living animals in the 

 laboratory. Preparations were made from the whole blood defibrinated 

 by beating; from blood kept liquid by oxalating; and also from mixtures 

 of whole blood and the blood plasma. The blood, either defibrinated or 

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

 solution thus obtained, with or without the addition of plasma, the slide 

 preparations were made. Two forms of crystallization were observed in the 

 oxyhemoglobin; the first, distinguished as a-oxyhemoglobin, is the normal 

 form and crystallizes in the orthorhombic system; the second, which is 

 designated as /2-oxyhemoglobin, is monoclinic. The a-oxyhemoglobin is 

 readily obtained by any of the methods of preparation above mentioned and 

 is very insoluble, the crystals continuing to form until the color is practically 

 discharged from the solution, and the slide is filled with a mass of needles 

 in most cases. When the preparation is thick, the crystals become so 

 massed together in the slides that the preparations are useless for crys- 

 tallographic investigation (see plate 72, fig. 429). The /3-oxyhemoglobin 

 crystals were only occasionally observed (in perhaps one out of a dozen 

 slides), and appeared to develop more readily in the blood to which no 

 oxalate had been added. Aside from this, no difference was noted in 

 preparations made with and without oxalate. All crystals became brownish 

 on standing under the cover for some days, and passed by paramorphism 

 into the metoxyhemoglobin, but without any change in their angles. 



a-Oxyhemoglobin of Canis familiaris. 



Orthorhombic: Axial ratio a : b : 6 =0.6745 : 1 : 0.2863; a : c = l : 0.4245. 

 Forms observed: Unit prism (110), macrodome (101), base (001). 

 Angles: Prism angle 110 A 110=68 (normals); macrodome angle 101 A 101=46 

 (normals) (also measured on some specimens as 44). 



