Serological Specificity of Race in the Domestic Eowl

Serological difference befween two races of domestic fowl, Long Tail or Yokohama (Gallus dom. pugnax longicaudatus) (Fig. 1) originated in Japan and White Leghorn (Gallus dom. livornensis) (Fig. 2), both pure adult hens, was examined by means of precipitin reaction.The blood serum from White Leghorn hens was repeatedly intravenously injected into many rabbits. The homologous blood serum (serum from White Leghorn) was carefully added to the rabbit-immunserum thus obtained on one side and the heterologous (serum from Long Tail) on the other, and the degree of precipitation in these two cases was compared. But the homologous and the heterologous blood sera were not distinguishable in this way, so the immunsera were specialized so that they would react only with the homologous blood serum and not with that of the heterologous. For this purpose a sufficient volume of the immunserum was added to the heterologous serum so that the rich precipitum occured, then the precipitum was centrifuged. Such immunserum is designated the "Specialized Immunserum" below.The degree of the precipitation can well be expressed numerically by the number of dilution of the blood serum, (when the number is large the precipita-tion with the immunserum is hardly shown), the original solution of the blood serum (protein content 2%) being 1, double diluted 2, four times diluted 3, eight times 4, and so on.The homologous and the heterologous serum reacted positively in the same degree with the immunserum (five examples) of White Leghorn, so the blood sera of these two races can not be distinguished by this means. The homologous serum, however, reacted as far as 7 with the specialized immunserum (five exam-ples), but the heterologous not at all in any example. Therefore the blood sera of these two races in the domestic fowl are clearly distinguished from each other, absolute specificity being given.