The study estimates the bactericidal power of blood by measuring the survival rate of Staphylococcus aureus after exposure to blood. Blood is tested by mixing it with bacterial cultures and measuring the number of surviving bacteria. The results are analyzed using statistical methods to determine the reliability of the measurements and to compare the bactericidal power of different blood samples. The study uses two methods to count viable bacteria: plate count and roll-tube count. A surface-viable count is also used, which involves measuring the number of colonies that develop on agar plates. The results are compared to a Poisson distribution to assess the accuracy of the counts. The study finds that Fildes' agar is the most suitable medium for measuring the bactericidal power of blood. It provides the highest counts and the most accurate results. The study also shows that the survival rate of bacteria can be affected by factors such as the age of the culture and the presence of agglutinin or phagocytosis. The study concludes that the survival rate of bacteria in blood is a reliable measure of the bactericidal power of blood. The results show that the bactericidal power of blood can vary between individuals and that the survival rate is influenced by factors such as the age of the culture and the presence of agglutinin or phagocytosis. The study also highlights the importance of using appropriate statistical methods to analyze the results and to ensure the accuracy of the measurements.The study estimates the bactericidal power of blood by measuring the survival rate of Staphylococcus aureus after exposure to blood. Blood is tested by mixing it with bacterial cultures and measuring the number of surviving bacteria. The results are analyzed using statistical methods to determine the reliability of the measurements and to compare the bactericidal power of different blood samples. The study uses two methods to count viable bacteria: plate count and roll-tube count. A surface-viable count is also used, which involves measuring the number of colonies that develop on agar plates. The results are compared to a Poisson distribution to assess the accuracy of the counts. The study finds that Fildes' agar is the most suitable medium for measuring the bactericidal power of blood. It provides the highest counts and the most accurate results. The study also shows that the survival rate of bacteria can be affected by factors such as the age of the culture and the presence of agglutinin or phagocytosis. The study concludes that the survival rate of bacteria in blood is a reliable measure of the bactericidal power of blood. The results show that the bactericidal power of blood can vary between individuals and that the survival rate is influenced by factors such as the age of the culture and the presence of agglutinin or phagocytosis. The study also highlights the importance of using appropriate statistical methods to analyze the results and to ensure the accuracy of the measurements.