246 M. R. IRWIN 



cells of one of the offspring, or the pooled cells of two or more, were made by 

 Mrs. Briles. Following the absorption of the antiserum obtained from either 

 parent by the cells of the other, it was noted that the absorbed antiserum was 

 at least weakly reactive with the cells of the individual from which the anti- 

 serum was obtained. That is, such an antiserum would not react (agglutinate) 

 with its own cells before absorption with the cells of the mate, but after such 

 absorption it definitely would agglutinate the cells of the individual from 

 which it was derived. 



To use a concrete example, bird R614 (containing Bi antigen) was im- 

 munized with the washed cells of R2C43, to produce B3 antibodies (Briles, 

 McGibbon, and Irwin, 1951). After this antiserum from R614 was mixed for 

 absorption with the washed cells of R622 (having B3 antigen in its cells and 

 having been immunized to produce Bi antibodies), all cells containing the Bi 

 antigen were reactive with it, including those of R614 itself. Thus it appears 

 that the antibodies to Bi which were circulating in the serum of R622 were 

 also attached to the surface of the red blood cells and were transferred to the 

 antiserum from R614 during the absorption process. It was possible to dem- 

 onstrate that, after washing the cells of R622 in saline, the saline contained 

 antibodies, even after nine successive washings. Hence, unless the cells of 

 both parents were used as controls in comparable tests for the presence of a 

 hybrid substance, agglutination of any cells could be explained as due to a 

 transfer of antibody from the blood cells to an antiserum. Unfortunately, 

 such controls are not given in Thomsen's paper, and the possibility cannot be 

 eliminated that the reactions obtained by him were due simply to segregation 

 within the various families of an antigenic character of one of the parents. 

 This possibility was mentioned by Thomsen (1936), but was not considered 

 applicable to his experiments. 



Hybrid Substances 



Returning to the hybrid substance for which there is definite evidence, it 

 should first be stated that such a substance has not been found in all kinds of 

 species hybrids, as may be seen from the data given in Table 15.2. It has been 

 reported from our laboratory in hybrids between Pearlneck and Ring dove, 

 the pigeon {Columba livia) and Ring dove, the Mallard {Anas platyrhynchos) 

 and Muscovy duck (Cairina moschata), but not in the hybrids between the 

 triangular spotted pigeon (C. guinea) and livia. Irwin (1947) gives the spe- 

 cific references to pertinent articles. 



A hybrid substance has been detected but not previously reported in 

 hybrids from malings between the Philippine turtle dove (St. dussumieri) 

 and Ring dove, the dwarf turtle dove {St. Jmmilis) and Ring dove, the 

 Oriental turtle dove {St. orientalis) and Ring dove, and the band tail pigeon 

 {C. fasciata) and livia. No such substance has been observed in the hybrids 

 between the Senegal dove {St. senegalensis) and Ring dove, an African dove 



