The cultivation of a chromogenic acid-fast bacillus from leprous lesions on Musgrave and Clegg's medium is confirmed.
Neither the symbiotic amoebae of Clegg nor the protein split products of Duval are necessary for the growth of this organism.
The essential factor for the development of Clegg's bacillus appears to be the lean medium containing only traces of nutrient substances.
Clegg's acid-fast bacillus develops in transplants from colonies of Bordoni-Uffreduzzi's partially acid-fast diphtheroid on Musgrave and Clegg's medium.
A chromogenic acid-fast bacillus, similar to Clegg's bacillus, develops in transplants from colonies of the pleomorphic diphtheroid from smegma praeputii on Musgrave and Clegg's medium.
A non-chromogenic acid-fast bacillus, having also morphological differences from Clegg's bacillus, develops in cultures from non-leprous nasal secretions and from Hoffmann's diphtheroid isolated from such secretions, on Musgrave and Clegg's medium.
Clegg's bacillus appears to be a developmental stage of Bordoni-Uffreduzzi's diphtheroid, but the possibility that it may be a contamination can not as yet be absolutely excluded.
Both Clegg and Bordoni-Uffreduzzi and their successors may have cultivated different forms of one and the same pleomorphic bacterium from leprosy.
This organism appears to be identical with or closely related to the pleomorphic and facultative acid-fast so-called Bacillus smegmatis.