OF PISCES, BATRACHIA, AND REPTILIA. 



157 



Habit at first prismatic, long lath-shaped crystals consisting of the prism (110) 

 and the base (001) ; these later develop the acute macrodome (401), showing then the com- 

 bination (110) and (401) with sometimes the base also (text figure 19). They gradually 

 give place to the tabular form, analogous to the second form of the metoxyhemoglobin. 

 The tabular form consists of the prism (110) and the base only, beginning as very thin 

 plates, but gradually becoming thick tables or blocks, due to the elongation of the prism. 

 The rods grow into sheaf-like tufts, but do not appear to twin on the macrodome as in 

 the metoxyhemoglobin form. The tabular crystals also aggregate into groups by parallel 

 growth on the base. 



Pleochroism is rather strong; a rose-pink, 6 rose-red, c deep red. Orientation 

 of the elasticity axes is as in the metoxyhemoglobin, a = b, b=a, c = <!; this orientation 

 is exactly the same in the prismatic and in the tabular habits. Extinction is symmetrical 

 on the basal aspect of the plates and straight in all other aspects; the interference figure 

 was not observed. 



BATRACHIA. 



NECTURUS, Necturus maculatus. Plates 6 and 7. 



The blood of Necturus was examined on a number of different occasions, 

 and was always freshly obtained by killing and bleeding the animal. Prep- 

 arations were made by various methods: in some the usual method of 

 oxalating and ether-laking was followed ; in some the blood was defibrinated 

 by beating it, and then it was ether-laked without the addition of oxalate; 

 to the defibrinated blood oxalate was added in the normal amount, and 



21 



FIGS. 20, 21, 22, 23, 24. Necturu* maculatus Oxyhemoglobin. 



the crystals from the oxalated and non-oxalated bloods compared. Beyond 

 differences in habit, no change in the crystallization was produced by the 

 variations in treatment. Both oxyhemoglobin and reduced hemoglobin 

 were obtained, but they seemed to crystallize in exactly the same form. 

 Many of the crystals were quite brownish, but the spectroscope failed to 

 reveal any methemoglobin. 



Oxyhemoglobin of Necturus maculatus. 



Orthorhombic: Axial ratio a : b : 6=0.6494 : 1 : 1. 



Forms observed: Prism (110), macrodome (110), brachydome (Oil); and in twins 

 (111). 



Angles: 110AlTO = 66; Oil A Oil =90; 10lAl01=66; from twin, angle of 

 pyramid 111 A TTl=58 (calculated 57 8'). 



