298 BACTERIOLOGY. 
tralize the effect of tuberculin when injected into tuber- 
culous guinea-pigs; but this test is insufficient and prob- 
ably valueless, since tuberculin is not the same as the 
unaltered products of the tubercle bacillus. Moreover, 
it has been shown by Trudeau and Baldwin that other 
substances which have no specific properties whatever 
will have much the same effect as the serum under 
certain conditions. Some make the further claim that 
guinea-pigs injected with serum acquire an immunity 
to the virulent tubercle bacilli, and that those already 
infected live longer than the controls which receive no 
serum; and some even claim to be able to cure animals 
eighteen days after inoculation with a culture of tu- 
bercle bacilli. Very few observers, however, have suc- 
ceeded in obtaining appreciable results with the serums 
prepared by other experimenters. In spite of such con- 
flicting testimony, it is probably safe to assert that no 
serums now obtainable have any great value. Nor as 
we look at the progressive nature of tuberculosis can 
we see much ground to hope for the abundant de- 
velopment of curative substances in the blood of ani- 
mals. 
Prophylaxis. Meanwhile all energies should be 
directed to the prevention of tuberculosis, not only 
by the enforcement of proper sanitary regulations as 
regards the care of sputum, milk, meat, disinfection, 
etc., but also by continued experimental work and by 
the establishment of free consumptive hospitals, and 
by efforts to improve the character of the food, dwell- 
ings, and condition of the people in general, we should 
endeavor to build up the individual resistance to the 
disease. It may be years yet before the public are 
sufficiently educated to co-operate with the sanitary 
