BACILLUS OF TUBERCULOSIS. 297 
of producing violent reactionary symptoms, and the 
graded increase of the subsequent doses within such 
quantities as are known never to produce reaction in 
healthy individuals, would seem to afford the best 
protection against unpleasant results and misleading 
evidence.”’ 
Antituberculous Serum. Whether serum-therapy is 
destined to solve the problem of the treatment of tuber- 
culosis remains for the future to decide, but up to the 
present the results obtained with antituberculous serum 
do not warrant our forming such an opinion. The at- 
tempts to obtain from animals—chiefly horses—a serum 
which would be protective have been carried out along 
very much the same lines as Koch’s experiments upon 
man. The methods adopted have been as follows: Old 
cultures of tubercle bacilli grown in 5 per cent. glycerin 
bouillon have been filtered either with or without pre- 
vious boiling, and then injected into animals, this 
process being similar to Koch’s with his first tuberculin. 
Others have injected living virulent or non-virulent 
tubercle bacilli, either alone or with their culture fluids; 
others still (Biichner) have injected the bacterial proto- 
plasm obtained by crushing tubercle bacilli together 
with sand and squeezing them ; this, like Koch with 
his new tuberculin, being an attempt to get from the 
unaltered products and cell-contents of the bacilli the 
formation in the body of bactericidal or immunizing 
substances. 
Among the many claiming good results in man or 
animals thus treated may be mentioned Hericourt, 
Richet, Bernheim, Maragliano, Viquerat, Paquin, 
de Schweinitz and Dorset, McFarland, and others. 
The majority claim for their serum the power to neu- 
