226 MICROBES, FERMENTS, AND MOULDS. 
in his turn attacked by phthisis. All these people 
resided in a place in which it was easy to verify the 
absence of hereditary taint.” 
Here are other observations of the same nature :— 
« A young woman without hereditary taint nursed 
a phthisical patient and contracted phthisis. She 
returned home, and communicated the disease to the 
six sisters with whom she lived. One sister survived, 
but she was not living with her family. 
“A soldier became phthisical while with his regi- 
ment, and was therefore discharged, and returned to 
his family. His father, mother, two brothers, and a 
neighbour who nursed them, became phthisical. Yet 
none of them were predisposed by hereditary taint. 
“A girl returned from school in consumption; on 
her death her room and clothes passed to her sister, 
who died of the same disease. A third sister died 
under like conditions. As their parents still survive, 
it is clear that the disease was not due to heredity.” 
This does not imply that heredity plays no part 
in the transmission of the disease, for the contrary is 
proved; yet such transmission often occurs after the 
child is born, and sometimes the nurse by whom it 
is suckled may be the source of contagion. : 
In the case of children brought up by hand, the 
infection may come from cow’s milk which has not 
been boiled. Cows are often attacked by tuberculosis, 
and numerous bacilli have been found in the teats and 
milk of these animals. This indicates the necessity 
