302 BIOCHEMICAL SYSTEMATICS 



several chromosomes of Pearlneck." It is evident that he considers it 

 Hkely that the antigenic sub-units are similar. 



McGibbon (1944) also found a specific hybrid-type antigen in 

 inter-specific crosses of ducks. He was able to produce antibodies to the 

 hybrid antigen in both parental species. Miller (1956) reported a 

 hybrid-substance of the blood cells of inter-generic hybrids between 

 the domestic pigeon {Columba livia) and the ring dove (Streptopelia 

 risoria). Columba livia had already been determined as having several 

 species-specific antigenic substances (A^, B^, C^ and E^) which segre- 

 gated as Mendelian characters, and in backcross hybrids the hybrid 

 substance was closely linked with the character C^. A particularly 

 interesting feature of this work is the fact that hybrid antisera, 

 adsorbed with pooled cells of S. risoria and C. livia (parental species), 

 still shows activity with a number of other related species and genera. 

 (Specifically, "the cells of eight of thirty species of Columbidae and 

 three other kinds of species hybrids were agglutinated strongly by the 

 reagent for this hybrid-substance prepared from antiserum 493F4.") 

 It is difficult to account satisfactorily for the presence of a "hybrid 

 antigenic substance" which is closely linked with another species- 

 specific antigenic substance (CMn this case). Miller appears to favor 

 some mechanism involving allelic interaction wherein the C^ allele 

 and a "C-like" allele, contributed by the other species, cooperate to 

 produce the hybrid antigen. At present no satisfactory experimental 

 test of such an hypothesis has been contrived. 



Scheinberg (1960) who studied serum antigens of pigeons, 

 turtle doves, and ring doves corroborated the previous findings that 

 specific antigens show Mendelian segregation. Furthermore, serum 

 antigens of bison, cattle, and bison-cattle hybrids were tested in the 

 conventional manner and also subjected to starch-gel electrophoresis. 

 Their illustrations show that the starch-gel pattern of the hybrid 

 possesses more distinguishable components than the sera of either 

 parental species. The electrophoretic patterns of the hybrids sug- 

 gested, according to the author, that the serum contained all of the 

 proteins present in each parental serum as well as additional compo- 

 nents only present in the hybrid serum. For turtle dove-ring dove 

 hybrids whose proteins were also studied by electrophoresis it was 

 concluded that the hybrid possessed all of the serum protein found in 

 the sera of each of the parental species. Illustrations pertinent to this 

 last point were not particularly good, however. 



Bacharach et al. (1960) have also found a "hybrid" substance 

 in hybrids of domestic fowl and pheasant. The hybrids apparently 

 possessed most antigens specific to each species and "probably all 

 those held in common." 



