In serum and chemotherapeutic investigations in bacterial infections, animals are usually infected by subcutaneous or intraperitoneal injections of the test microorganism resulting in the production of generalized infections associated with bacteremia and terminating fatally in a few days, or in a few weeks, as in experimental tuberculosis. As a general rule, the test animals are very susceptible to the test microparasite, and the results are evaluated by the duration of the lives of treated animals as compared with infected but untreated controls.
In experimental serum therapy of such bacterial infections as are produced by virulent pneumococci, streptococci, meningococci, anthrax bacilli, and so forth, this method is generally satisfactory because owing to the low toxicity of the immune serums for the test animals, relatively large amounts may be given to influence favorably an otherwise rapidly fatal bacteremia and septicemia. But in chemotherapeutic studies in bacterial infections the dosis curativa of a