M.S.

As <i>in vivo</i> study of the alteration of the erythrocytes from forty-six young chickens of various breeds infected with tree strains of Newcastle disease virus has been made. Three strains of Newcastle disease virus which varied in their pathogenicity for chickens, namely B1, N1, and N2 strains, have been studied, comparing the agglutinability of the red blood cells by the tube hemagglutination method and the rapid-plate technique. Graphs and tables have been prepared showing the <i>in vivo</i> effect of the virus strains on the chicken crythroeytes when the viral strains are used as the agglutinating agent. By mixing a drop of whole blood with 0.05 ml. of the B1 strain of Newcastle disease virus formalized with 0.10% formalin it may be possible to diagnose Newcastle disease in chickens, without the aid of the standard hemagglutination-inhibition (HI) test. The author believes that with more study the plate method may be of real value as a screening or presumptive test in the diagnosis of Newcastle disease infection. / M.S.