OF PISCES, BATRACHIA, AND REPTILIA. 151 



Habit of the crystals long lath-shaped (text figure 3) , the length 20 to 30 times the 

 breadth, which latter is about 4 times the thickness. The crystal appears to consist of 

 the two pinacoids, terminated by a flat dome. This is probably the brachydome. Its 

 interfacial angle was measured very roughly as 110, giving the angle between face 

 normals as 70. The large plane in the prismatic zone is then taken as the brachypinacoid 

 (010), and the smaller plane, visible when the crystal is on edge, is hence the macropina- 

 coid. On the flat, the long lath-shaped crystal has square ends, measured as 90 with 

 the sides; and on edge the flat brachydome terminates the crystal. 



Pleochroism is rather strong; for a, the direction of greatest elasticity, which is 

 parallel to the length, the color is pale yellowish; b and c are nearly equal, and the color 

 is reddish-brown. Extinction is straight in both the edge view and on the flat or side 

 view. The polarization and pleochroic colors are not interfered with by the color of the 

 plasma, as practically all of the hemoglobin crystallizes. Between crossed nicols, the 

 colors seen on the flat ranged from blue-slate of the first order up to straw-yellow and 

 orange of the first order in the different thicknesses of crystals, indicating a moderately 

 strong double refraction. No interference figure was observed. 



SHAD, Alosa sapidissima. Plates 2, 3, and 4. 



Shad blood was obtained by bleeding the living fish, and also by ob- 

 taining blood from dead fish purchased in the market. In the former case 

 it was either oxalated or allowed to clot; in the latter it was obtained in 

 the form of clots from the larger vessels, etc. The clotted blood was treated 

 by oxalating and ether-laking, and also by grinding the clot with sand and 

 ether-laking, centrifugalizing, and oxalating the clear blood. The fresh 

 oxalated blood, either laked by ether and centrifugalized, or the corpuscles 

 broken down by repeatedly freezing and thawing the blood, always showed 

 a combination of methemoglobin and oxyhemoglobin, the material often 

 described as "methemoglobin." Much difficulty was experienced in get- 

 ting rid of the nuclei of the corpuscles by centrifugalizing, but this was 

 partly overcome by using thoroughly clotted blood and breaking up the 

 clots by grinding in sand. On allowing the blood to stand in a corked tube 

 in the refrigerator, the blood usually passed largely into reduced hemoglobin. 

 The blood that was freely exposed to the air and had been kept for some 

 days, or the deoxidized blood exposed to the air, and, finally, the clotted 

 blood obtained from fish that had died in the air and had been dead a 

 few days, as obtained in market, always contained some methemoglobin 

 which would crystallize as such and not as metoxyhemoglobin. 



It would seem, therefore, that the blood of the shad during the spawn- 

 ing season, in which it is obtained in our rivers, contains a large proportion 

 of methemoglobin in combination with oxyhemoglobin, or a substance inter- 

 mediate between oxyhemoglobin, methemoglobin, and metoxyhemoglobin; 

 and that further exposure to air changes this to pure methemoglobin in part, 

 leaving a residue of pure oxyhemoglobin, which two substances may be crys- 

 tallized simultaneously from the blood in distinct crystals of pure methemo- 

 globin and pure oxyhemoglobin, which substances do not form in the freshly 

 drawn, slightly oxidized blood. This occurrence of metoxyhemoglobin in 

 the freshly drawn blood may be due to the state of inactivity that the 

 digestive organs of the animal are in during the spawning season, as the 

 fish do not feed during this time. The same condition in the blood is noted 

 in the case of bears, for example, during the hibernating period. 



