20 
Guinea pig No. 112 . — Blood drawn twenty-five days after infection. 
General tuberculosis at autopsy. 
Whole heart’s blood on glycerin potato gave no growth of tubercle 
bacilli. Eight c. c. whole heart’s blood into guinea pig Xo. 112A. 
weight 280 grams; died sixty days later, weight 450 grams; general 
tuberculosis at autopsy. 
SUMMARY AND DISCUSSION. 
An examination of the above experiments shows that there were 
47 cases of pulmonary tuberculosis in which tubercle bacilli were 
found in the sputum and one case of joint tuberculosis in which the 
bacilli were not foimd. From these 48 cases of human tuberculosis 
glycerin-potato cultures, guinea-pig inoculations, and smears were 
made from the sediment obtained by centrifugation; but in not a single 
instance were tubercle bacilli demonstrated either by the examination 
of the smears, cultures, or animal inoculations. 
Glycerin-potato cultures, guinea-pig inoculations, and smears were 
made in 35 of the 48 cases from the sediment obtained by placing the 
citrated blood in the ice chest for twenty-four hours. In one instance 
(case Xo. 1) the smears showed an organism that had the morpho- 
logical and tinctorial appearances of tubercle bacilli; but the glycerin- 
potato culture and guinea-pig inoculations were negative. The 
smears made from the centrifugalized sediment in the same case 
were negative. 
Thirty-five of the 48 cases had smears, cultures, and animal inocu- 
lations made from the sediment obtained both by the centrifuge and 
by gravity for twenty-four hours in the ice chest. 
In onlv a few instances was there a growth in the fermentation 
i o 
tubes in seventv-two hours, showing that bv care in the collection 
and handling of the blood contamination mav be avoided in the 
CD 
great majority of cases. 
If tubercle bacilli had been present in sufficient numbers in the 
blood to be detected in smears, it would certainly seem that they 
should have been found in more than one instance in this series of 48 
cases, in 47 of which tubercle bacilli had been found in the sputum. 
In most cases 2.5 c. c. of the sediment, either obtained by the cen- 
trifuge or by gravity, or both, were inoculated into guinea pigs, and 
this amount was many times the amount used to make the smears, 
yet all the animals inoculated were negative. 
The glycerin-potato cultures were also uniformly negative. That 
the failure to find tubercle bacilli in the blood from these cases by 
animal inoculation, even when not found in smears, was not due to 
a bactericidal action of the serum is negatived bv case Xo. 38 and 
by the experiments with the blood of rabbits experimentally infected. 
To a portion of the citrated blood from case Xo. 38 a very small 
