CARRIAGE OF DISEASE 
163 
smears were taken from the thoracic duct which indi¬ 
cated tubercle bacilli, thus showing how easily these 
bacilli can enter the general circulation. 
Dr. Frederick T. Lord (1904), after a series of long 
and careful laboratory investigations, reached the fol¬ 
lowing conclusions: 
“1. Flies may ingest tubercular sputum and excrete 
tubercle bacilli, the virulence of which may last for at 
least fifteen days. 
“2. The danger of human infection from tubercular 
fly-specks is by the ingestion of the specks on food. 
Spontaneous liberation of tubercle bacilli from fly- 
specks is unlikely. If mechanically disturbed, infec¬ 
tion of the surrounding air may occur. 
“As a corollary to these conclusions, it is suggested 
that— 
“3. Tubercular material (sputum, pus from dis¬ 
charging sinuses, fecal matter from patients with intes¬ 
tinal tuberculosis, etc.) should be carefully protected 
from flies, lest they act as disseminators of the tubercle 
bacilli. 
“4. During the fly season greater attention should 
be paid to the screening of rooms and hospital wards 
containing patients with tuberculosis and laboratories 
where tubercular material is examined. 
“5. As these precautions would not eliminate fly in¬ 
fection by patients at large, foodstuffs should be pro¬ 
tected from flies which may already have ingester tu¬ 
bercular material.” 
According to Nuttall and Jepson, the first investi- 
