Abstract
Streptomycin, isoniazid, viomycin, and oxytetracycline were most effective against susceptible tubercle bacilli when active multiplication is taking place. These agents are capable of exerting little or no antimicrobial effect on tubercle bacilli existing in a dormant or non-multiplying phase. When streptomycin and isoniazid were used sequentially, the 2d drug was fully active provided those organisms surviving contact with the 1st drug were capable of cell division.