CHAPTER XV. 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF THE 

 CANID^E DOGS, WOLVES, AND FOXES. 



Twelve members of the family Canidoe were studied, representing 10 

 distinct species, and two varieties or crosses. Some of the species were 

 represented by several specimens, so that their crystals could be studied 

 under different methods of preparation. As a group, the dogs possess 

 hemoglobins of a rather insoluble character, the crystals form readily and 

 they do not readily dissolve. All members of the family furnished oxy- 

 hemoglobin crystals which closely resembled each other, so that the differ- 

 ences between species were not readily made out. All the crystals, without 

 exception were orthorhombic, and the optical character was negative in 

 each case. The axial ratios were so nearly alike, especially the ratio of 

 a : c, which was determinable in each case, that, in spite of the fact that the 

 zoologists place the 10 species examined in three different genera, they show 

 much less difference among themselves than is common with the species 

 of a single genus. 



Six species and two varieties of the genus Cam's were studied, also three 

 species of the genus Vulpes, and the gray fox Urocyon. Of the genus Cam's, 

 the species examined included the common dog, Cam's familiaris; the 

 chow dog, a variety of the same species; a cross between the coyote and 

 a collie dog; the gray wolf, Cam's lupus mexicanus; the coyote, Cam's 

 latrans; the jackal, Canis aureus; the dingo, Cam's dingo; and Azara's 

 wild dog, Canis azarce. This list of dogs includes animals from Europe, 

 Asia, and Australia, besides those from North and South America. In spite 

 of this wide range, however, the species examined show a remarkable 

 resemblance in their crystals. The four foxes studied were the Swiss fox, 

 Vulpes vulpes, the American red fox, Vulpes fulvus; the Arctic or blue fox, 

 Vulpes lagopus, and the gray fox, Urocyon cinereoargenteus. 



The general type of crystal, common to all species of this family, is a 

 more or less elongated prism, with a diamond-shaped cross-section, and 

 usually strongly striated longitudinally, terminated by a rather flat dome. 

 The striation of the prism is due to the tendency of the crystals to form in 

 needles and aggregate into bundles of crystals; and this makes the dome 

 terminations rather small, so that the angles, on which the crystallographic 

 constants are based, are only determined with some difficulty. The prism 

 angle is still more difficult to observe, as cross-sections are hard to find 

 that are sufficiently symmetrical for trustworthy measurements; and all 

 examinations of angles must be made with a moderately high-power objec- 

 tive. On account of these difficulties of measurement, the complete axial 



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