330 BACTERIOLOGY. 
tried to show that “‘ croup”? and pharyngeal diphthe- 
ria were different diseases, or, in bacteriological terms, 
due to different micro-organisms, and this subject re- 
mained under controversy until it was recently settled 
that while most cases were undoubtedly due, at least 
to a great extent, to diphtheria bacilli, a few were not. 
Bard, an American, supported, in 1771, the opposite 
theory from Home, considering the process the same 
wherever located. In this ground he was much nearer 
to the facts than Home. His observations upon diph- 
theria were very important and accurate. 
In 1821, Bretonneau published his first essay on diph- 
theria in Paris and gave to the disease its present name. 
His observations were so extensive and so correct that 
little advance in knowledge took place until the causal 
relations of the diphtheria bacilli and their associated 
micro-organisms to the disease began to be recognized. 
Since then the combined clinical, bacteriological, and 
pathological studies have sufficed to make diphtheria 
one of the best understood of diseases. 
The Bacillus. In the year 1883 bacilli which were 
very peculiar and striking in appearance were shown 
by Klebs to be of constant occurrence in the pseudo- 
membranes from the throats of those dying of true 
epidemic diphtheria. One year later Loffler published 
the results of a very thorough and extensive series of 
investigations on this subject. He found the bacillus 
described by Klebs in many cases of throat inflam- 
mations which had been diagnosticated as diphthe- 
ria. He separated these bacilli from the other bac- 
teria present and obtained them in pure culture. When 
he inoculated the bacilli upon the abraded mucous mem- 
brane of susceptible animals, more or less characteristic 
