AND PREVENTION OF PITTIIISIS. 407 



handkerchief, was visited by Cornet. During her life- 

 time he proved the dust of her room to be infectious. 

 Sis weeks after her death he again visited the dwelling. 

 Rubbing the dust from a square meter of the wall on 

 which he had formerly found his infectious matter, and 

 which had not been cleansed after the woman's death, 

 h inoculated with it three of his guinea-pigs. Ex- 

 amined forty days after the inoculation, two of the 

 three were found tuberculous. Cornet reasons thus : 

 'No doubt the dust which had thus proved its virulence 

 would have retained it for a longer time. Schili and 

 Fischer, indeed, have proved that, after six months' 

 preservation, dried sputum may retain its virulence. 

 During this period, therefore, the possibility of infection 

 by this dust is obviously open. When, moreover, the 

 quantity of infectious matter inhaled is very small, a 

 considerable time elapses before the development of the 

 bacilli renders the malady distinct. Even if a year 

 should elapse after the death of a phthisical patient 

 before another member of the same household shows 

 symptoms of lung disease, we are not entitled to assume 

 a hereditary tendency without further proof. Aware of 

 the facts above mentioned, we ought rather to ascribe 

 the disease to infection by the dwelling, not to mention 

 its possible derivation from, other sources.' 



On January 14, 1888, Cornet visited a patient who, 

 for three-quarters of a year, had suffered from tuber- 

 culosis of the lung and larynx. The dust of the room 

 occupied by this man was proved to contain virulent 

 infective matter. A brother of the patient who, at the 

 time of the examination of the dwelling, was alleged to 

 be in perfect health, exhibited phthisis of the larynx 

 four months afterwards. ' We are surely,' says Cornet, 

 ' warranted in ascribing this result, not to heredity, or 

 any other hypothetical cause, but to the naked fact that 



