Abstract
A simple technic has been developed for measuring PR8 influenza virus growth on preparations of chorioallantoic membranes together with the attached shell, removed from chicken embryos. 1) The maximum growth assayed by hemagglutinin was fairly constant. 2) The technic is simpler and less laborious than the usual method in which they used peeled chorioallantoic membranes from the shell. 3) During the continuous study for almost one year, there have been almost no chance of bacterial contamination. 4) Deviation of pH value from tube to tube after 24 hrs incubation was largely eliminated owing to the existence of shell.
