<prompt> Which of the following range shows the generation time for leprosy bacillus?8-10 days10-12 days12-15 days15-20 days  <response>: M. leprae cell division is by transverse fission. In mice, and presumably in man, it divides every 12-13 days growth rate, mean generation or doubling time. This is a uniquely slow rate of multiplication even for slow-growing mycobacteria M. tuberculosis, which also belongs to the slow-growing group, divides in about 20 hours, and is consistent with the long incubation period of the disease and its chronicity. 