Summary and Conclusions
Bacteriophage mixed with antibacteriophage serum and incubated twenty-four hours at 37°C. or longer shows the following properties:
Filtered through the colloidal sac, it does not influence bacterial growth.
It does not penetrate an average agar layer in a Petri dish, but it penetrates it where mixed with normal serum or alone.
It is precipitated with 13.5 per cent sodium sulphate, but remains in the filtrate, when mixed with normal serum or alone.
Bacteriophage is not destroyed by its union with the antibacteriophage serum.
When a mixture of bacteriophage and antibacteriophage serum is digested with trypsin the bacteriophage appears again active.