36 ESSAYS ON BACTERIOLOGY. 



not been reached. Tlie establishment of the possibil- 

 ity of bacilli remaining long inactive in the body has 

 given the advocates of heredity, of whom Baumgarten 

 is the leader, a firmer ground for their belief. In 

 addition to the case of Johne, a few more of hered- 

 itary transmission in animals have been recorded, and, 

 it is claimed, one in man. Were I asked to express 

 an opinion upon this matter, I would almost repeat my 

 former words: that there is a growing belief that the 

 older ideas of heredity are exaggerated; that the dis- 

 ease is to be looked upon as an infection rather than 

 an inheritance; that it is comparatively rarely trans- 

 mitted from parent to child in utero; adding, how- 

 ever, the opinion that the doctrine of heredity is as 

 yet by no means overthrown. We must still wait for 

 the whole truth. 



In the second group of diseases I include those 

 whose bacterial cause has in all probability, but not 

 absolutely, been established. These are leprosy, chol- 

 era, typhoid, relapsing fever, pneumonia, diphtheria, 

 gonorrhoea. 



It is doubtful whether the leprosy bacilli have ever 

 been successfully ciiltivated, but transplantation of 

 leprous tissue containing them has repeatedly been 

 followed by a reproduction of the bacilli and the dis- 

 ease. Nor have the spirilla of relapsing fever been ob- 

 tained by artificial culture. They are, however, al- 

 ways present in the blood in the disease, and success- 

 ful inoculation is always followed by their appearance 



