The Tubercle Bacillus. 
9.1 
sdmption, and other forms of tubercular disease. On January 14, 
1891, Koch announced that the substance employed in his 
anti-tubercular treatment was a glycerine extract of pure cultiva- 
tions of the tubercle bacillus. This extract now bears the name 
of tuberculine. 
Koch, after pointing out that the effective substance in 
this extract could be precipitated by absolute alcohol, stated 
that " for application in practice, this purification of the gly- 
cerine extract offers no advantage." This would indicate 
that Koch regarded the isolation of the active material in 
a pure state as superfluous. It seemed to the writer, who had 
been simultaneously investigating the products of the tubercle 
bacillus, a matter of great scientific interest to determine, if 
possible, the chemical properties and physiological effects of the 
separated products. In a conjoint investigation with Mr. 
Herroun, the products of the tubercle bacillus in pure cultiva- 
tions in glycerine-broth have been shown to contain albumose 
and an animal alkaloid, or ptomaine. 
It is much to be regretted that the details of experiments 
with tuberculine on animals have not been published by Koch, 
and that details are wanting of the chemical properties of the 
substance or substances contained in his extract. The hope 
that the extract would prove a curative agent has almost 
overwhelmed the scientific side of the subject, and the informa- 
tion which is most likely to be of real value is probably that 
which has hitherto been withheld from publication. 
Effect of Tuberculine ox Healthy and Tubercular 
Animals. 
With the assistance of Dr. Abraham, who was cne of the first 
to receive Dr. Koch's liquid from Berlin, the writer injected 
guinea-pigs with centigramme doses. Two tubercular guinea- 
pigs and one healthy one have been treated since January 7. Two 
other guinea-pigs in the same stage of tuberculosis were killed 
and carefully examined, both macroscopically and microscopic- 
ally, as a guide to the condition of the internal organs in the 
cases selected for treatment. The first injection in the tuber- 
cular guinea-pigs caused rise of temperature, swelling of the 
diseased glands, and redness of the surrounding skin. The 
second and subsequent injections produced a rise of temperature 
and tenderness, but no sudden glandular swelling. In one 
guinea-pig, which had been inoculated with bovine tuberculosis, 
the tubercular glands steadily increased in size. The tempera- 
ture reaction was most marked after the fourth injection, when 
