OF THE DOGS, WOLVES, AND FOXES. 



279 



acter very distinctly, and in what looks like single crystals it can often be seen that these 

 are a number of individuals in parallel growth. The observed macropinacoid appeared 

 to be a definite plane; but it could readily be a pseudo-plane, produced by this tendency 

 of the crystals to grow together on the brachypinacoid and to flatten on the macro- 

 pinacoid. In the retarded crystallizations (the diluted preparations of specimen II) 

 both the capillary crystals and also the normal crystals show a tendency to form into 

 more divergent groups, in some cases, as well as to form the parallel groups already 

 described; but the spherulitic masses of fibers, seen in many species of Cants, are not 

 common. These larger crystals are rarely short; and are very frequently single individ- 

 uals, with a ratio of length to thickness of 30 : 1 or 20 : 1; the tendency to produce 

 parallel growths results rather in the formation of bundles or masses of such single crys- 

 tals of rather irregular outlines, than in the formation of striated single crystals. While 

 the number of individuals in these bundles is usually only about 50 to 60, many of them 

 contain hundreds of crystals in parallel position, all extinguishing simultaneously. 



Pleochroism is marked when the crystals are seen with the smaller angle of the 

 prism pointing forward, or on edge; but not so strong when seen on the flat, looking 

 along a. The pleochroic colors are n pale reddish, b and c nearly equal and deep red to 

 pale red according to the thickness. Extinction is straight in all side views of the prisms 

 and symmetrical on cross-sections. The orientation of the elasticity axes is a=a; b=6; 

 c=<i. The axis of greatest elasticity is evidently the acute bisectrix of the optic axes, 

 Bx a =a, and the optical character is hence negative. 



TABLE 44. Crystallographic characters of the hemoglobins of the Canidce. 



