Table I.

Five dilutions of influenza virus tested on 8 allantoic sections.

10−2	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10−3	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10−4	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10−5	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes
10−6	No	No	No	No	No	No	No	No

Five dilutions of influenza virus were tested on 8 allantoic sections (40 tests in total). The maximal dilution of influenza virus causing hemagglutination (+) was 10⁻⁵. Allantoic sections contain an inhibitor of hemagglutination, and this method is a standard assay of virus infectivity. The data shown are from the study by Denys and Bocian (21).