August 30, 1912] 



SCIENCE 



283 



study of the lesions induced experimentally, 

 the behavior of the cultures with respect to 

 immune sera and by other well-known meth- 

 ods it is hoped that the proper status of the 

 various cultures will be established. 



In Louisiana I have attempted the cultiva- 

 tion of the Hansen bacillus from 29 cases of 

 leprosy and have succeeded in isolating an 

 acid-fast bacillus from 22 of these cases. The 

 chromogenic variety was recovered from 14 

 cases while 8 yielded a non-chromogenic acid- 

 fast bacillus which thus far has refused to 

 produce pigment or multiply on the ordinary 

 laboratory media, and in one case a non-acid- 

 fast diphtheroid was recovered. 



For many generations the sub-plants both 

 of the chromogenic and of the non-pigment 

 producing types have each remained well 

 within the variations of a species and have in 

 general maintained very closely the morphol- 

 ogy of the Hansen bacillus as we know it in 

 the tissues. 



In the 14 cases above mentioned the acid- 

 fast culture recovered has eventually under- 

 gone a marked change in morphological and 

 cultural features after which it could be prop- 

 agated upon the ordinary laboratory media. 

 These cultures which become chromogenic 

 correspond in all essentials to Clegg's original 

 isolation. 



In the 8 cases referred to, the non-chromo- 

 genic culture, although behaving much as did 

 the Clegg chromogenic bacillus for the first 

 two or three months under artificial growth 

 conditions, has refused to produce pigment or 

 grow on ordinary media. 



Since the chromogenic culture behaved 

 much in the same manner as the non-chromo- 

 gen during the first three or four months of 

 artificial cultivation, I have looked for a sim- 

 ilar change to occur in this particular " slow- 

 growing " strain. It would seem that it will 

 not become saprophytic as the period of para- 

 sitism experienced with the cultures which 

 subsequently became chromogenic and dis- 

 tinctly vegetative has long passed. 



It is hard to explain the occurrence in the 

 leprous lesion of the chromogenic acid-fast, 

 which in my experience with cases here is en- 



countered more frequently than the non- 

 chromogenic variety. Curiously enough the 

 chromogenic type, if we are to regard it as an 

 extraneous organism, is always the same va- 

 riety, that is, a moist rapidly growing diplo- 

 coccoid bacillus when once it becomes accus- 

 tomed to an artificial environment. I have 

 compared the seven original cultures of Clegg, 

 and those isolated independently by workers 

 in Hawaii, Honolulu and London with the 

 chromogenic cultures isolated here and find 

 them identical except for minor inconstant 

 differences. That the chromogen exists in the 

 lesion of certain types of leprosy there can be 

 no doubt, even where the overlying skin is ap- 

 parently intact, and also in the internal or- 

 gans at autopsy, more particularly the spleen. 

 If these cultures are extraneous saprophytes 

 it is hard to explain that they should occur in 

 so large a percentage of cases. Of course it 

 is well known how ubiquitous are the sapro- 

 phytic acid-fast species, it being possible to 

 isolate them from almost any source outside 

 the animal body. Their occasional occur- 

 rence, therefore, in the open skin lesion of 

 leprosy is to be expected, but to find them so 

 frequently is difficult to explain if we are to 

 accept that they are in no way concerned in 

 leprosy. 



The initial multiplication in vitro of both 

 the acid-fast strains referred to is accom- 

 plished with comparative ease, provided that 

 the bits of leprous tissue transferred are 

 treated in such a way that the protein moiety 

 is split into its dissociate products. 



This action upon the protein of the removed 

 leprous lesion may be accomplished in the fol- 

 lowing ways: (1) By seeding the tissue trans- 

 plants with some one of the putrefactive bac- 

 teria or with any species capable of hydro- 

 lyzing the tissues; (2) by saturating the re- 

 moved tissue bits with a one-per-cent. trypsin- 

 ized albumen solution ; or (3) by transferring 

 the leprous material directly to a medium 

 containing the products of protein digestion. 



With any of these methods the acid-fast 

 bacilli in bits of the removed lesion will multi- 

 ply and continue to do so as long as these 

 products are present. 



