PLATE 55 



Oxyhemoglobin of the Black Rat (Mus rnttus), showing twin on the flat, consisting of t\\i> individ- 

 uals and not producing a hexagonal plate as in White Rat twin. 



.'i'-'ii. Same, showing thicker crystals and olilique termination of dome faces. 



>-7. Oxyhemoglobin of the Alexandrine Rat (Mux alc.randri>ius), showing unsymmetrical flattened prisms 

 and a twin on flat aspect to lower left of field. 



3'JX. Same, showing four-, five-, and six-sided tabular crystals, due to unsymmetrical development of dome 

 faces. 



329. Same, showing star-shaped twins. 



330. Same, showing larger crystals. 



