RELATIONS OF BACILLI TO DISEASE. 257 



numbers. In the sheaths of the nerves in the anaesthetic 

 form they are comparatively few in number, and in the 

 sclerosed tissue it may be impossible to find any. There 

 are few also in the skin patches referred to above as occur- 

 ring in this form of the disease. 



Their spread is chiefly by the lymphatics, though distri- 

 bution by the blood stream also occurs. They have been 

 said to be found in the blood during the presence of fever 

 and the eruption of fresh nodules, and they have also been 

 observed in the blood vessels post mortem, being chiefly 

 contained within leucocytes. Recent observations (e.g., 

 those of Doutrelepont and Wolters) show that the bacilli 

 may be more widely spread throughout the body than was 

 formerly supposed. A few may be detected in some cases 

 in various organs which show no structural change, especially 

 in the capillaries. The brain and spinal cord are practically 

 exempt. 



Relations to the Disease. Attempts to cultivate the 

 leprosy bacilli outside the body have so far been unsuccess- 

 ful. From time to time announcements of successful culti- 

 vations have been made, but one after another has proved 

 to be erroneous. A similar statement may be made with 

 regard to experiments in animals. If a piece of leprous 

 tissue be introduced subcutaneously in an animal, such as 

 the rabbit, a certain amount of induration may take place 

 around it, and the bacilli may be found unchanged in appear- 

 ance weeks or even months afterwards, but no multiplication 

 of the organisms takes place. The only exception to this 

 statement is afforded by the experiments of Melcher and 

 Orthmann, who inoculated the anterior chamber of the eye 

 of rabbits with leprous material, the inoculation being 

 followed by 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. 



