50 



richest supply of bacilli and their spores, and if it be borne 

 in mind how carelessly this dangerous matter is treated, how 

 it is scattered about the streets, the workrooms, the office 

 floors, aye, and even the bedrooms, a source of infection will 

 be found so great that none other need hardly be looked 

 for. 



One gets an idea of the virulence of this expectoration 

 when we know that it retained its infective power six weeks^ 

 although kept moist and putrefaction had set in. 



If the sputum was dried, on the other hand, it was found 

 virulent by experiments on guinea pigs six months after 

 being coughed up when kept from the action of the air. 



Intermittent freezing and melting does not interfere with 

 the power of trausmittiug the disease. It must not be sup- 

 posed, however, that these tubercle bacilli are scattered about 

 us without any choice or difference, but rather ths^t they are 

 principally found in narrow circumscribed regions, the centre 

 of which is a tubercular person. 



Ransome and Williams have been able to demonstrate the 

 bacillus from air collected in the ventilating shaft of the 

 Brompton Consumption Hospital, and inoculation experi- 

 ments from the dust collected on the floor of this hospital 

 have proved the infection to be present in the form of spores 

 when the microscope had failed to show the bacillus. 



Klein kept some guinea pigs in the ventilating shaft of th& 

 same hospital and they contracted the disease also. 



Dr. George Cornet, in G-ermany, has found the bacillus in 

 the dust of the street, but he points out a further source of 

 infection from the handkerchief used by the consumptive. 

 Here the sputum gets dried after repeated usage, and he has 

 been able to get the bacilli from the bedclothes on which the 

 handkerchief had lain during the night. 



Strange to say, that although the walls in hospital wards 

 where consumptives are kept have been found to be infected, 

 other patients who may be suffering from some acute affection 

 of lungs are still accommodated in many hospitals in the 

 same wards as the consumptives. 



Not only through the sputum may the air become infected, 

 but also by the breath of the patient. When bacilli are 

 given off by the breath they gradually sink, being heavier 

 than the air, and as the temperature of the air is rarely suffi- 

 ciently high to maintain their vitality active infection is not 

 carried far in this way. There is nevertheless a great risk in 

 the immediate inhaling of the breath of a consumptive, as 

 might occur to anyone sleeping with an invalid. 



(2.) Infection by the Alimentary Canal is perhaps the 

 second most important mode of infection, and the disease in 



