TEXT-BOOK OF BACTERIOLOGY. 247 



able rrom each other by their behavior when treated with the ordi- 

 nary aqueous anilin solutions. The former are as sensitive to them 

 as are the majority of all micro-organisms. With fuchsin or 

 methyl-violet in particular it is easy to obtain good preparations. 



When we speak of the rod-cells regularly observed in leprosy as 

 " lepra bacilli," we are raising to a certainty that which in point of 

 fact is only a very high degree of probability. It is true that these 

 bacilli are found in all cases of leprosy, and generally, too, in very 

 great numbers, and also that they are found only in cases of lep- 

 rosy. If we then take into account the similar symptoms and 

 other conditions peculiar to tuberculosis, one is perhaps justified in 

 concluding that here, too, the bacilli are the cause of the affection. 

 But this opinion cannot be proven. 



For there is as yet no well-established case in which it has 

 proved feasible to cultivate the bacilli outside the body, and still 

 less to reproduce the disease by the aid of such cultures. 



Some recently-published facts would seem to contradict this 

 assertion, and an Italian investigator, Bordoni Uffreduzzi, has re- 

 ported some experiments which certainly deserve attention. He 

 succeeded in obtaining from the marrow of the bones of a man who 

 had died of leprosy a rod bacterium which at incubator tempera- 

 ture grew slowly on hardened blood-serum with the addition of pep- 

 tone and glycerin, and which he proclaimed to be the lepra bacillus. 

 It stained in the specific manner — i.e., it was susceptible to the 

 ordinary staining matters — but when treated with anilin-fuchsin did 

 not lose its color again under the influence of acids, thus completely 

 fulfilling in this respect the conditions which we should expect to 

 find in the real lepra bacillus. 



The micro-organism grew, as already mentioned, but slowly on 

 the artificial culture medium, and it was not till after several days 

 had elapsed that a commencement of development was visible in 

 the incubator. The colonies appeared as little round plates, of 

 whitish-gray color, with thickened centre and irregular, jagged 

 edges. The stab-culture showed wax-like, slightly-yellow coating, 

 which did not liquefy the serum. 



Attempts at transmission to animals, which were made in the 

 most varied manner, all remained unsuccessful. Bordoni explains 

 this by the supposition that the bacillus outside the body very 

 quickly becomes a prey to natural attenuation; that in exchanging 

 its parasitic for a saprophytic mode of life it loses all its virulence. 



Several circumstances, indeed, would seem to favor the correct- 

 ness of this view. Though the bacillus at first developed only at 

 incubator temperature, on a foo4 medium specially and carefully 



