INFECTIOUS PNEUMONIA. 
331 
posed to the same conditions, as in stables where a large number 
of horses are kept. Thus, at the barracks in Berlin, in Germany, 
in the year 1890, an epidemic of infections pneumonia occurred 
in which 79 horses were attacked, and again in the same bar¬ 
racks in 1892, a similar epidemic of infectious pneumonia broke 
out in which 55 horses were attacked ; there are also numerous 
records of epidemics in different sections of Europe during the 
years 1893 and 1894. Sometimes these outbreaks would occur 
in different countries at the same time. But it does not follow 
that these outbreaks bear any direct relation to each other. On 
the contrary, everything indicates that the infectious agent in¬ 
duces these outbreaks at various intervals. Without stopping to 
discuss further the facts relating to the epidemic prevalence of 
the disease under consideration, I will call attention to the 
well-established fact that pneumonia prevails over a wide area 
of the inhabited surface of the globe ; we must therefore con¬ 
clude, that if pneumonia is a specific infectious disease, the micro¬ 
organism which causes it is widely distributed. As a matter of 
fact, the pathogenic micrococcus which, from the evidence now 
at hand, appears to be the specific etiological agent in acute in¬ 
fectious pneumonia, has been found in the buccal secretions of 
healthy animals in various parts of the world. This statement 
may appear at the outset to make the view that the micrococcus 
in question is the cause of infectious pneumonia quite untenable. 
For, it may be asked, how is it that the animals who have this 
micro-organism in their buccal secretions escape an attack of 
pneumonia. I11 the present state of our knowledge, this ques¬ 
tion no longer presents any serious difficulties. We know, for 
example, that the pus-organism staphylococcus pyogenes aniens, 
albus and citreus are very frequently found in the buccal secre¬ 
tions and 011 the surface of the body of healthy animals, and 
that, although these micrococci are recognized as the cause of 
all sorts of acute abscesses, they only give rise to the formation 
of such abscesses under certain special conditions relating to the 
general health of the animal. It is well known that the tetanus 
bacillus is found in rich loam in various parts of the globe, and 
