OF THE DOGS, WOLVES, AND FOXES. 



267 



Habit prismatic, elongated parallel to the vertical axis, and the prism terminated 

 by the flat dome (101) (text figure 293) or sometimes by the base (text figure 294). The 

 first crystals to form are usually hair-like, but stouter crystals later develop along the 

 protein ring and the cover edge. These stouter crystals may also appear in the body 

 of the slide, and may even be doubly terminated. They are often seen to be composite, 

 by parallel growth in the zone of the vertical axis; and are strongly striated in this 

 direction, because of the parallel growth. Cross-sections are rare, and almost never 

 appear in measurable form until the slides are several days old. The ratio of length 

 to thickness varies from 500 : 1 in the hair-like crystals, down to 20 : 1 in some of the 

 stouter crystals. Twinning was not observed, but a parallel growth, in which the crystals 

 grow together upon the brachypinacoid, is very commonly seen. In such groups two 

 prisms are seen in perfectly parallel orientation, and united side by side on the brachy- 

 pinacoid. This is a character quite common in all of these rod-like orthorhombic crystals 

 in other species also. 



Pleochroism is marked; a nearly colorless, 6 rather pale red, c deep red. Double 

 refraction is strong; and extinction is straight in all side views and symmetrical on 

 cross-sections of the prism. The orientation of the optic axis a=a, b=6, c=6. No 

 interference figure was observed; but, from the relative elasticities in different directions, 

 it would appear probable that the optical character was negative and the acute bisectrix 

 Bx a =a. 



(3-Oxyhemoglobin of Cam's familiaris. 



Monoclinic: Axial ratio not determined, ,3=78. 



Forms observed: Unit prism (110), clinopinacoid (010), orthopinacoid (100), 

 basal pinacoid (001). 



Angles: Orthopinacoid to base 100 A 001=78=/?; the prism angle appears to 

 be acute on a or a > 6, but no cross-sections were found from which this angle of the 

 prism could be obtained. 



Habit (a) prismatic on the vertical axis, the crystal consisting of the unit prism, 

 clinopinacoid, and base (text figure 295); the crystals rather large and well-formed; also 

 (b) tabular on the clinopinacoid, 

 the crystal consisting of the three 

 pinacoids only, with the base and P** 1 

 orthopinacoid in equilibrium; thus 

 making a rhomboidal plate (text 

 figure 296). Both kinds of crys- 

 tals, types (a) and (b) , were found 

 very sparingly, in a preparation of 

 defibrinated blood without oxalate; 

 the plate-like crystals of type (b) 

 were seen still more sparingly in a 

 preparation in which oxalate was 

 used. Often preparations of defi- 

 brinated blood failed to develop 

 these crystals. 



Pleochroism is very strong; a 

 pale yellowish-red, b rose-pink, c 

 deep blood-red. Double refraction 

 is strong, and the extinction, meas- 

 ured from the prism edge, is 15. The orientation of the optic axes is as follows: a A a =27 

 in the obtuse angle; b=b; c A c = 15, in the acute angle. Looking at the crystal, normal 

 to the orthopinacoid, in convergent light, one brush of the interference figure is seen, 

 showing that the axis of greatest elasticity is the acute bisectrix Bx a =a, and the optical 

 character is hence negative. The plane of the optic axes is the plane of symmetry, and 

 the axis of mean elasticity is the ortho-axis. The crystals twin on a prism, and are 

 frequently seen so twinned, in such a position that the extinction is symmetrical to the 



293 



295 



297 



294 



FIGS. 293, 294. Canis familiaria a-Oxyhemoglobin. 

 FIGS. 295, 296. 297. Canis familiaris |S-Oxyheraoglobin. 



