282 



SCIENCE 



[N. S. Vol. XXXVI. No. 922 



More recently Bayon (1912) describes a 

 non-acid-fast diphtheroid obtained from a 

 leper which behaves in a like manner to 

 ICedrowski's culture, i. e., the initial growth 

 from the tissues is non-acid-fast and a diph- 

 theroid until passed through rats, after which 

 it permanently changes into a typical acid- 

 fast bacillus. Like Eost and Williams he also 

 mentions streptothrical forms in his culture. 

 He concludes that not only is his culture 

 identical with Kedrowski's, but also that it is 

 the cause of human leprosy, basing his argu- 

 ment upon specific reactions obtained with 

 human leper serum and also upon the pro- 

 duction of characteristic lesions in laboratory 

 animals. 



Clegg in 1909 announced his success in the 

 cultivation of an acid-fast bacillus which he 

 isolated from lesions in a large series of lepers 

 in the Philippines. He found that multi- 

 plication in each instance occurred in the 

 transferred leprous tissue bits when planted 

 with amoeba and their symbionts. He subse- 

 quently obtained pure cultures of acid-fast 

 organisms on the ordinary laboratory media 

 as a moist, profuse, pigmented growth after 

 heating at 60° C. for 30 minutes to kill out 

 the symbionts. 



The author (1910) described a method by 

 which the bacilli in the leprous lesion could 

 be cultivated in vitro without the use of 

 symbionts. The culture differed from Clegg's 

 in that it did not produce pigment and it re- 

 fused to grow except upon special nutrients; 

 however, cultures were subsequently isolated 

 from a number of cases which in time became 

 rapid growers and chromogenic. Other cul- 

 tures similar to Clegg's have been reported by 

 Brinkerhoff and Currie in Honolulu, Eivas in 

 Philadelphia, Thompson in Australia, Well- 

 man in California and workers in Hawaii. 



The work of Eost, Williams, Kedrowski, 

 Bayon and others, who have cultivated organ- 

 isms other than acid-fast rods from leprous 

 lesions, tends to show that the organism of 

 leprosy is " an extremely pleomorphic strepto- 

 thrix " which under certain circumstances 

 may be: (1) A non-acid-fast streptothrix with 



interlacing filaments, (2) a non-acid-fast 

 diphtheroid bacillus, which is in reality a 

 streptothrix, and capable of becoming acid- 

 fast under certain conditions, (3) a definite 

 acid-fast filamentous streptothrix, or (4) an 

 acid-fast bacillus which is the broken-down 

 stage of a streptothrix. 



A review of the literature would seem to 

 show that three or possibly four apparently 

 different germs have been cultivated and de- 

 scribed as the causal agent of human leprosy; 

 namely, (1) a non-acid-fast diphtheroid 

 (Kedrowski), (2) an acid-fast chromogenic 

 bacillus (Clegg), (3) non acid-fast and acid- 

 fast interlacing and filamentous streptothrix 

 (Eost & Williams), and (4) a bacillus which m 

 vitro maintains the morphology and staining 

 reaction of the Hansen bacillus of the tissues 

 and grows under artificial conditions only in 

 the presence of special nutrients (Duval). 



Acid-fast and non-acid-fast filamentous 

 forms I have also encountered in certain of 

 the cultures which become chromogenic and 

 rapid growers, but branching non-acid-fast 

 streptothriees I have never noted in the acid- 

 fast culture which is non-chromogenic and 

 refuses to multiply except upon special media. 



The marked variation in morphology and 

 staining properties of the chromogenic cul- 

 ture I have regarded as involution or degene- 

 ration forms of the species. However, it is 

 noteworthy that by plating out the chromo- 

 genic culture, separate colonies of non-acid- 

 fast streptothriees and non-aeid-fast diphthe- 

 roids are recovered, and these are converted 

 into acid-fast rods by alterations in the reac- 

 tion of the medium, etc. 



Since we may encounter in the leprous 

 lesion a pleomorphic organism which is ca- 

 pable of changing in vitro under defined con- 

 ditions, it is easy to explain the bewildering 

 number of " stages " for the supposedly culti- 

 vated Hansen bacillus of some writers. 



Whether the various cultures reported as the 

 Hansen bacillus represent the same or dis- 

 tinct species, some one of which is the real 

 exciter of leprosy and the others simply ex- 

 traneous or accidental commensals, is a prob- 

 lem yet unsolved; however, by a comparative 



