 However, work on leprosy was frustrated by the inability to culture the leprosy bacillus in the laboratory.Twort suspected that the leprosy bacillus had a 'close relationship' with the tubercle bacillus, a species that was culturable.Twort wrote, "It appeared highly probable that these two organisms would require the same chemical substances for building up their protoplasm, which could be elaborated from the ordinary media only
by the tubercle bacillus."