1. Probably in the majority of cases it is possible, with scrupulous technique, to isolate the tubercle bacillus from contaminated material such as the sputum, by the method outlined by Petroff.
2. It is necessary to use several tubes.
3. Neutralization, drying, temperature of the incubator, and contamination after the growth has started are important points to be noted in the process.
4. The colonies start as pin points, becoming larger and confluent, but still preserving individual groups of a dry appearance which simulate the medium closely in color.
5. The bacillus of tuberculosis in young culture is tinctorially acid-fast and of a polymorphous morphology.