CHAPTER X. 



CRYSTALLOGRAPHY OF THE HEMOGLOBINS OF AVES. 



The hemoglobin crystals of 10 species of birds were examined, 2 species 

 belonging to the subclass Ratitce or flightless birds, and the remainder to 

 the subclass Carinatce or flying birds. The Ratitce examined were the 

 African ostrich, a representative of the Struthionidce ; and the cassowary, a 

 member of the Casuariidce. The carinate birds represented 4 orders, and 

 were distributed as follows : Anseres, 3 species, the goose, trumpeter swan, 

 and whistling swan; Gallince, 3 species, chicken, Virginia quail, and guinea- 

 fowl; Columbce, 1 species, the carrier pigeon; and Passcres, 1 species, the 

 crow. 



It will be noticed that this is not a representative list of birds, but it 

 includes examples from the two principal subclasses, the Ratitce and the 

 Carinatce. Of the 23 orders of living birds ordinarily recognized but 5 are 

 represented in this list. In the case of the Anseres the 3 species are closely 

 related and 2 belong to the same genus, thus permitting of close compari- 

 son. In the Gallince, too, are 3 species usually regarded as closely related. 

 Two of these, the chicken and quail, will be seen to resemble each other 

 closely, but the third, the guinea-fowl, is quite far removed from them as 

 shown by its hemoglobin crystals. Indeed, the crystals of the guinea-fowl 

 show closer resemblance to those of the African ostrich, one of the Ratitce, 

 which in its zoological relations is generally regarded as far removed from 

 the Gallince. The chicken and quail crystals, however, show some resem- 

 blance to those of the Anseres, and even to the Columbce. The one passerine 

 bird studied gave crystals that were quite different from any of the others 

 examined. 



The table given at the end of the chapter shows some of the characters 

 of the crystals of the oxy hemoglobin of the birds examined, and it will be 

 noticed that, with two exceptions, they are either orthorhombic or tetrag- 

 onal. In the detailed descriptions which follow it will be shown that the 

 orthorhombic crystals have a tendency to become pseudo-tetragonal (or 

 not distinguishable from tetragonal) by mimetic twinning ; so that it seems 

 very likely that the two species recorded as tetragonal may in reality be 



only pseudo-tetragonal. 



AVES. 



AFRICAN OSTRICH, Struthio camelus. Plate 8. 



The sample of blood was received from the National Zoological Park 

 at Washington in an exceedingly putrid condition, and clotted. The clot 

 was rubbed in sand, with addition of ether, and the mixture centrifugalized. 

 But a small quantity of the clear liquid was obtained, from which slides 



11 161 



