136 MICRO-ORGANISMS AND DISEASE. [CHAP. 



Quite recently I have ascertained that pigs inoculated 

 with artificial cultures of these rods (started from the pig, 

 mouse, or rabbit dead of the plague) or with the diseased 

 organs of a mouse or rabbit, suffer from a mild form of the 

 disease, which after one or two weeks passes off completely. 

 I have had pigs that had been twice inoculated, the first 

 time with artificial cultures, the second time with diseased 

 organs of mouse and rabbit, and each time the pigs suffered 

 from a mild form of the disease. They were then inocu- 

 lated a third time with the juice of the diseased (fresh) lung 

 of a pig dead of the plague ; this time also they showed 

 distinct symptoms of the disease, but after a few days to a 

 week they completely recovered. If normal (or not pre- 

 viously inoculated) pigs are inoculated with matter from the 

 diseased fresh lung of a pig dead of the plague, they as a 

 rule die from a virulent form of the disease. But in the 

 above case they were protected by previous inoculations, 

 not altogether against a new attack but against a fatal 

 attack. 



(i) Bacillus Leprcz. Armauer Hansen 1 first ascertained 

 the existence of large numbers of minute bacilli in the 

 peculiar large leprosy-cells of Virchow, which occur in the 

 nodules of leprous patients. Neisser confirmed this, and 

 considerably extended our knowledge of the bacilli, showing 

 that they can be readily stained pink with ftichsin or with 

 Ehrlich's acid solution of eosin-hsematoxylin. The bacilli 

 are fine rods about 0*004 to 0*006 mm. long and less than 

 o-oo i mm. thick. They are pointed at their ends, and 

 always occur in masses within the large leprosy- cells of the 

 leprous tubercles of the skin and internal organs. But they 



1 Virchmv's Anhiv> vol. Ixxix. ; and Quart, Journ. of Micro. Sci. 

 1880. 



