272 CRYSTALLOGRAPHY OF THE HEMOGLOBINS 



Habit at first (when the crystallization is proceeding rapidly) capillary, long tri- 

 chites which are quite flexible and have a ratio of length to thickness of 1000 : 1 or more; 

 as the crystals begin to form more slowly the thickness increases and in crystals in the 

 protein ring and along the cover edge, as well as in scattered crystals throughout the 

 body of the slide, this ratio falls to 10 : 1 and even to 5 : 1. The hair-like 

 crystals grow felted together irregularly and in spherulitic groupings radiating 

 from a common center (see plate 75, fig. 445). In some cases these trichites 

 are resolved, but in most of the slides they persisted for days. The thicker 

 normal crystals are strongly striated parallel with the length (parallel to the 

 vertical axis, <!), as is usual in this genus; and they were evidently bundles of 

 crystals aggregated together in parallel growth. But some of the crystals 

 appearing throughout the body of the slide were apparently single crystals 

 (text figure 305), although of measurable size. They were not vertically 

 striated. All of the larger crystals showed only the long prism (110) and 

 the macrodome (101); but frequently in the groups the dome became so 

 reduced that the crystal was seen to be terminated by a pseudo-base due to 

 the parallel grouping. When the parallel growth resulted in the members of 

 the group uniting on the brachypinacoid (and hence the group flattening par- 

 305 allel to the macropinacoid) the domes were not so noticeable, and again the 

 crystal appeared to be terminated by the base. No definite twins were observed. 

 aureut Pleochroism was not very marked when looking normal to the macro- 



pinacoid, but when looking along the macro-axis it was very strong. The colors 

 were: a pale yellowish-red; b rose-pink; c pale to deep red, according to the 

 thickness. When the crystal was observed on the brachypinacoid aspect, looking along 

 the macro-axis and with a and c in the field, the colors were: a pale yellowish-red, c deep 

 (scarlet) red. In the aspect at 90 to this, with b and c in the field, the colors were: b 

 rose-pink, c pale scarlet, and the colors of 6 and c were nearly equally strong. Extinction 

 is straight in all aspects normal to the vertical axis and no cross-sections were seen. The 

 double refraction is rather strong. No interference figure was observed. The orientation 

 of the elasticity axes is a =a; b =6; c =<{. The acute bisectrix of the optic axes is evidently 

 the axis of greatest elasticity, Bx a = a, and the optical character is negative. 



DINGO OR AUSTRALIAN WILD DOG, Cam's dingo. Plates 75 and 76. 



The specimen of blood was received from the National Zoological Park 

 at Washington, District of Columbia, and was from a pup. The blood was 

 clotted and putrid, and was evidently stale when placed in our collecting 

 tube with oxalate. The specimen was ground in sand with ether to destroy 

 the clot, a little normal saline solution added, and the ground mixture 

 centrifugalized for several hours. From the clear solution thus obtained 

 the slide preparations were made as usual. Crystallization proceeds very 

 rapidly after the slides are covered, the first crystals to form being rather 

 short rods, but later longer crystals developed. The crystals formed at 

 room temperature show no signs of dissolving, but the slides kept overnight 

 at a temperature below freezing developed crystals that dissolved until 

 equilibrium in the solution was reestablished. When kept at room tempera- 

 ture fairly large crystals formed in the protein ring and along the cover 

 edge, and short trichites appeared through the body of the slide. The 

 crystals are evidently quite as insoluble as is commonly the case in this 

 genus. They are oxyhemoglobin as determined by the microspectroscope. 



