ETIOLOGY OF TUBERCULOSIS. 
255 
tered lor human food or devouring parts of unburied car¬ 
casses. 
Dogs and chickens further propagate the disease by pick¬ 
ing up the sputum of the human phthisis, and the pig by 
consuming the offal or by drinking the urine of affected 
cattle. Rats and mice, by acquiring the disease about slaugh¬ 
terhouses, may transmit it to the dogs and cats devouring 
them. 
The entrails of chickens, tainted with tabes mesenterica, 
frequently prove the death morsel of dogs, cats or pigs. 
The abraded skin may be the first organ affected by the 
germ-carrying dust settling on the parts, or by saliva from 
the tongue. 
Also, there is a possibility of animals, suffering from ec¬ 
zema, mange or lice, by frequenting a common rubbing-post, 
spreading the complaint by inoculating one another in the 
form of lupus, which tends to become disseminated from the 
corium of the derma through the lymphatic and blood vas¬ 
cular systems. 
All the minor surgical operations furnish a means of prop¬ 
agating the evil, unless at all times strict antiseptic precau¬ 
tions be taken, for either the operator, the assistant or the 
nurse may be phthisical. 
Circumcision of the infant has resulted fatally from a like 
cause. The germs may find entrance by a cavity in the cari¬ 
ous tooth and eventually gain access to the systemic circula¬ 
tion. 
These methods may seem too trivial to warrant mention, 
but it is well known to surgeons that large wounds are not ? 
while small wounds are, readily susceptible to the action of 
the virus. 
In regard to its heredity much has been written from the 
remotest times down to the present day. Cases of congeni. 
tal tuberculosis with definite symptoms and lesions at birth 
have seldom, I believe, been reported, and in general the 
tendency only to this dread disease is inherited. This is in 
accord with the anatomy and physiology of the reproductive 
organs, for if the semen contained numerous bacilli, which 
