XI 



tion often determines the seat of the disease. The bacillus, or spords, 

 that dry up and lie about are otten inhaled into the body. The 

 sputum of tubercular persons usually furnishes the richest supply of 

 bacilli and their spores, and is often very virulent. Ransome and 

 Williams have been able to demonstrate the bacillus from air collected 

 in the ventilating shaft of the Brompton Consutr.ptive Hospital, and 

 inoculation experiments 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 fhow the bacillus. Klein kept some 

 guinea pigs on the ventilating shaft, and they contracted the disease 

 also. Then the spores may be communicated by the breath of the 

 patient. Infection by the alimentary canal is, perhaps, the second 

 important mode of infection, and the disease in this way may be com- 

 municated by means of milk or meat from diseased animals. Doubt 

 no longer exists about milk from tubercular cows beiog the means of 

 conveying tuberculosis, particularly to infants and young children. 

 It is now considered inadvisable for consumptive mothers to suckle 

 their infants, for although tubercular disease of the mammary gland 

 is somewhat rare in the human subject, it would seem that the 

 infecoion may be conveyed without this organ being diseased. The 

 danger of contracting tuberculosis from meat is not so great as the 

 taking of milk from tuberculous cows, but it is nevertheless a source of 

 infection if meat is not properly cooked. When the disease is localised 

 it ia thought by some that there is little risk of eating the part of the 

 carcase unaffected, but Professor McCall, of Glasgow, has shown that 

 the bacilli, although not having their habitat in the blood, have been 

 found there as well as in the marrow of bones. The authorities in 

 Glasgow, acting on this, condemn the whole carcase. The parts in 

 close proximity to the disease may be contaminated, while the parts 

 at a distance may not. Inoculation is fortunately not a very common 

 mode of infection. It has followed from a cut on the finger with 

 a broken spittoon used by a phthisical patient. Medical men doing 

 post-mortems, butchers, and cooks have been infected in the execution 

 of their duties in this way. It is said to have resulted in two cases 

 from tattooing where the saliva of a phthisical patient was used. 

 The question whether tuberculosis can be transmitted from parent to 

 child is one which authorities are divided upon. Many observers 

 hold that the disease cannot be transmitted, but only a predis- 

 position, and heredity to such as Virchow and Frankel only means 

 greater predisposition, but to Klein it means the actual transmission of 

 the disease. It has seldom been found in calves, and rarely in new 

 born infants. While tuberculosis may be transmitted directly from 

 parent to child, there is a very strong consensus of opinion that the 

 form which affects the lungs is never so transmitted. It may then be 

 taken for granted that ••consumption is not hereditary, but only a 

 predisposition — what that predisposition is we cannot yet say." Weak- 

 ness of the constitution sets up a predisposition. Certain conditions, 

 such as dampness of soil, impurity of atmosphere, are important 

 factors. Dr. Buchanan and Sir John Simon have long since proved that 

 •* the drying of soil, which has in most cases accompanied the laying of 

 main sewers in the improved towns, has led to the diminution, more or 

 less considerable, of phthisis," and this has been abundantly proved 

 as the result of town improvements. Dampness of soil and seaboard 

 towns are favourable predisposing agents of tubercular disease. It 

 would seem as if the bacilli were there in greatest numbers and 

 most deadly in effects. Localities with dry soils and uniform tempera- 

 ture are least affected. Nothing tends to predispose to tuberculosis so 

 much as a vitiated atmosphere. This is evidenced by the fact that 

 we have consumption most common in large cities ; not only so, but 

 in the parts of them where overcrowding and bad ventilation are at a 



