132 APPLIED BACTERIOLOGY 



at a temperature of 35° to 37° C, on which it forms ' a 

 light yellow stripe with irregular edges along the needle 

 track.' The serum is never liquefied, and no growth ever 

 occurs in the condensation water. On glycerine-agar 

 plates, both on the surface and deeply in the medium, 

 colonies may be seen with a power of 100 diameters which 

 are gray net-like growths with irregular edges.* 



Bordoni-Uffreduzzi found that the organism grew only 

 with difficulty at blood-heat on the serum, but after re- 

 peated subculture appeared to adapt itself more readily to 

 a saprophytic condition of life, and finally could be sub- 

 cultured on the gelatine. The inoculation of leprotic 

 culture into animals seems to produce no effect at all, 

 which would differentiate it from tubercle, and also appear 

 to indicate that leprosy is exclusively a human disease. It 

 is unknown how the bacillus is conveyed : and the causa 

 vera of leprosy still remains unsettled. There seems to be 

 much evidence to prove that it is not spread by contagion 

 or heredity, though there are examples which appear to 

 favour both. This matter was so carefully investigated by 

 the Leprosy Commission in India that it may be well to 

 repeat here their conclusions (Leprosy Commission in India 

 Eeport, p. 384) : 



(1) ' Leprosy is a disease sui generis ; it is not a form of 

 syphilis or tuberculosis, but has strictly etiological analogies 

 with the latter. 



(2) ' Leprosy is not diffused by hereditary transmission, 

 and for this reason, and the established amount of sterility 

 among lepers, the disease has a natural tendency to die out. 



(3) ' Though in a scientific classification of diseases 

 leprosy must be regarded as contagious, and also inoculable, 

 yet the extent to which it is propagated by these means is 

 exceedingly small. 



* Leprosy Commission Eeport, p. 425. 



