CONTAGIOUSNESS OF TUBERCULOSIS. 
825 
Consumption is preventable. This should be the cry all over the 
land. For many years it was held that consumption was inherited, in 
which belief it was but natural to stand by and take no precautions 
to prevent the spread of the disease. We now know that the disease 
is not inherited. As a rule, with very few exceptions, the bacillus 
itself does not pass from parents to offspring before birth.* The 
inheritance bequeathed from consumptive parents is the marked 
tendency to contract the disease when exposed to the exciting cause. 
When the parents are affected with tuberculosis the children from the 
earliest moments of life are exposed to the disease, under the most 
favourable conditions for its transmission ; for not only is the dust of 
the house very likely to coutain bacilli, but the close and intimate 
relations between parents and children, especially mother and baby, 
are particularly favourable for transmission of the disease by direct 
contact. The frequent occurrence of several cases of tuberculosis in 
a family is explainable not by the supposition that the disease has 
been inherited before birth, but because it lias been acquired since, 
and probably from the parents. 
The parasite — the Bacillus tuberculosis — is present wherever there 
is tubercular disease ; it is found in all tissues in which tubercular 
disease is active. The expectoration and other secretions of the air- 
passages in all persons and animals whose lungs, throats, mouths, or 
nostrils are the sites of tubercular disease, practically speaking, always 
contain tubercle bacilli. In tubercular kidney disease the urine may 
contain tubercle bacilli ; the bowel discharges when tubercular ulcera- 
tion of the intestines is present; the discharges from tubercular 
abscesses, bone disease, &c. 
Cornet has shown by his experiments that in the rooms where 
consumptives live tubercle bacilli are frequently present in the dust on 
the Avails, floors, and furniture. He practically found no tubercle 
bacilli in the dust of the rooms of those consumptives who carefully 
spat only into spittoons, and not on to the floor or into handkerchiefs. 
By the experiments of Dr. Bansome, reported in a paper read 
before the Boyal Society, and by the experiments of others, it appears 
that the breath of a consumptive very rarely, if ever, contains tubercle 
bacilli, but during coughing, by the chance scattering of mucus, 
tubercle bacilli may be ejected, and so become a source of danger to 
persons around. 
From animals to man contagion is spread chiefly through cow’s 
milk, and by eating the flesh of tubercular animals. Bollinger and 
Hirschberger, in Europe, and Ernst, of Boston, II. 8. America, have 
found that the milk of cows affected with pleural or pulmonary 
tuberculosis can infect guinea-pigs even when the udders are perfectly 
normal, and the cows themselves are in a very good state of nutrition. 
When the udders themselves are the seat of tubercle, the milk is then 
infective in a very high degree. It is very important to appreciate 
this evidence, for it means that it is never safe to use for food the 
flesh or milk of an animal suffering from even localised tuberculosis. 
The explanation may be that tubercle bacilli are circulating in the 
blood — i.e., the virus is becoming disseminated through the general 
* Hiller, at the Copenhagen Congress, 1884, reported having observed one congenital 
case in the human subject. In the case of animals several instances have been 
recorded of the transmission of tubercle from the cow to her calf before birth. 
