RELATIONS TO THE DISEASE 303 



an extensive growth of nodules in the lungs and internal organs, 

 which they affirmed contained leprosy bacilli. It has been 

 questioned, however, by several authorities whether the organisms 

 in the nodules were really leprosy bacilli, and up to the present 

 we cannot say that there is any satisfactory proof that the 

 disease can be transmitted to any of the lower animals. Diph- 

 theroid bacilli of more than one variety have been cultivated 

 from the blood and tissues of leprous patients by Babes and 

 others. Their presence would appear to be by no means in- 

 frequent, but it is not possible to say at present what their 

 significance is. 



It is interesting to note that a disease occurs under natural 

 conditions in rats which presents many points of close similarity 

 to leprosy. It is very widespread, having been observed in 

 Europe, Asia, America, and Australia ; an excellent description 

 has been given by Dean. In this affection there are lesions 

 in the skin which resemble those in leprosy, and the cells con- 

 tain enormous numbers of an acid-fast bacillus. The disease 

 can be transmitted to rats by inoculation with the tissue juices 

 containing the bacilli, but not to animals of other species. All 

 attempts to cultivate the characteristic organism outside the 

 body have failed, but Dean has obtained a diphtheroid bacillus 

 a result of interest in relation to what has been found in 

 leprosy. Whether this disease has any relation to leprosy in the 

 human subject is very doubtful, but the facts which have been 

 ascertained may prove of high importance in connection with 

 the pathology of the latter disease. 



It would also appear that the disease is not readily inoculable 

 in the human subject. In a w r ell-known case described by Arning, 

 a criminal in the Sandwich Islands was inoculated in several 

 parts of the body with leprosy tissue. Two or three years later, 

 well-marked tubercular leprosy appeared, and led to a fatal result. 

 This experiment, however, is open to the objection that the 

 individual before inoculation had been exposed to infection in a 

 natural way, having been frequently in contact with lepers. In 

 other cases, inoculation experiments on healthy subjects and 

 inoculations in other parts of leprous individuals have given 

 negative results. It has been supposed by some that the failure 

 to obtain cultures and to reproduce the disease experimentally 

 may be partly due to the bacilli in the tissues being dead. That 

 many of the leprous bacilli are in a dead condition is quite 

 possible, in view of the long period during which dead tubercle 

 bacilli introduced into the tissues of animals retain their form 

 and staining reaction. There is also the fact that from time to 



