1650 



LEPROSY 



taken from places frequented by lepers, the majority have failed 

 to find them; and, again, what has been remarked with regard to 

 air also applies to dust. The germs have never been found in the 

 water of the most highly infected places. 



Many articles of food have been suspected, especially fish, and 

 more particularly salted fish — a view which Sir Jonathan Hutchin- 

 son has strongly advocated; but even he admits that it will not 

 explain all cases, particularly its presence in people who have no 

 chance of eating cured fish. 



After excluding all these, there is still the possibility of the in- 

 fection being carried by some blood-sucking insect. This subject has 

 been most ably discussed by Nuttall, who points out that Linn3eus 

 and Rolander considered Chlorops {Musca) leprcB to be the active 

 agent; while Corredor suspected flies in general; Sabrazes, insects; 

 Joly, Sarcoptes acahiei and Pediculi ; and Sommer, mosquitoes. 

 Nuttall himself says that the possibility of such transmission 

 cannot be denied. Goodhue has demonstrated the bacilli in Culex 

 pungens and in Clinocoris lectularius ; and Marchoux and Bourret 

 have suggested that some vSimuhida^ might be the carriers of the 

 •disease. Fhes, lice, bugs, fleas, ticks, etc., have all been studied 

 recently without any great success. 



It might be thought that, direct inoculation having failed, the 

 infection by means of insects would be unhkely. But that is not 

 so, because it is well known that the passage of bacilli through 

 another animal may markedly modify the virulence of the germ. 

 On the other hand, a great many facts are in favour of the insect 

 spread of the disease — e.g., the infection in a family. The cases 

 cited above as examples of contagion would be easily explicable 

 by the action of an insect, as would the effect of isolation in pre- 

 venting the disease. Moreover, the predisposing causes of dirt, 

 poverty, etc., are also explicable on the same reasoning, especially 

 the curious disappearance of the disease in the families of Nor- 

 wegian peasants emigrating to America, where they became much 

 cleaner in their habits. The difficult}^ of cultivating the germ on 

 ordinary media is very suggestive of its being accustomed to live 

 'solely in animal tissues; while the abundance of the bacilli in the 

 skin is also suggestive of that being the natural method of leaving 

 the body. Ever^^thing in the history of the disease appears to us to 

 favour its spread by animal agency. 



Cases of infection by vaccination and variolization are on record. Natives 

 of Ceylon generally state that the disease begins after a bite by a rat. 



Pathology. — According to different theories, the bacillus enleis 

 the body via the skin, the nasal or respiratory mucosae, the ali- 

 mentary canal, or the generative organs. 



The list is so comprehensive that it will be obvious that the real 

 method of entry is entirely unknown. On arrival inside the body, 

 the bacillus is supposed to come to rest inside a lymph space some- 

 where, and there to grow and form colonies, from whence it can be 



