The basic lab tests performed on the sputum sample are the same today as they were back in the days of the sanatoriums. Once a sputum sample is obtained from the patient, at least three procedures are performed. First a smear is made and stained in such a manner that tubercle bacilli may be identified by examination under the microscope. Secondly, a portion of the gastric washings is treated to destroy any secondary infection, and the resulting sediment is divided in two portions, one to be plated on culture media, which is especially prepared for the growth of tubercle bacilli, and the other half is used for animal inoculation. Tubercle bacilli are very slow growing organisms so we must wait a period of from three to six weeks for the results of the culture and the animal inoculation.