In preceding papers (Irwin, '32 ; Irwin and Cole, '36 ; Irwin, et al., '36) from this laboratory, it has been pointed out that for each of two different pairs of dove and pigeon species, respectively, the erythrocytes contain numerous antigenic substances in common, but are readily differentiated by the substances which are species-specific, i.e., not found in the cells of the other species. References to related reports may be found in the above papers.
Methods
The domesticated form of the common pigeon (Columba livia) and the domesticated Ring dove (Streptopelia risoria), belonging to families Columbidae and Peristeridae, respectively, have been under study by one of us (L. J. C.) for several years as regards their fertility in crosses and the genetic principles underlying the appearance of males only in crosses of male pigeons (livia) to Ring doves. For brevity, the species will be generally referred to as livia and R. D., respectively. The serological investigations have been performed by the senior author. l Paper no. 194 from the department of genetics, Agricultural Experiment Station, University of Wisconsin. Published with the approval of the Director of the Station. This investigation was supported in part by a grant from the Committee for Raearch in Problems of Sex, National Research Council. 'Mr. C. D. Gordon, research assistant in genetics, haa given much valuable aid in these experiments. 309 * Zoijt ( '35) has reported a change i n immunological specificity resulting from the union in vitro of the serum proteins of two animal species.