ACTINOMYCOSIS 255 
cosis to a suppurative process combined with granulation tissue 
formation, the pus of which contains the characteristic granules com- 
posed of the dense aggregation of the organisms. 
Cattle (genus Bos) are most often attacked. Horses, dogs, cats, 
sheep, elephants, bears and the human family are susceptible and 
cases have been reported in each. Other species seem to be immune. 
History. The early history of actinomycosis is quite obscure. 
Prior to the discovery of its specific cause, it was much confused with 
other diseases resembling it more or less closely in certain gross 
appearances. It was designated by a variety of names, the more 
common of which are swelled head, lumpy jaw, big head, fibroma, 
sarcoma and osteosarcoma. The popular names were probably sug- 
gested by the character of the lesions, which differ to a marked degree. 
It was recognized as a specific disease by Rivolta in 1868, by Perron- 
cito in 1875 and by Bollinger in 1877, The ray fungus was un- 
doubtedly observed prior to this by Lebert and Robin, both of whom 
failed to recognize it as a vegetable parasite. 
The fungus was carefully described by Dr. Harz, a botanist, who 
gave it the name Actinomyces or ray fungus. Bollinger was the first 
to carefully study the disease in cattle and to demonstrate the power 
of the ray fungus to produce disease. With this discovery of Bollinger 
in 1877, actinomycosis became recognized as a definite, specific disease 
which could in most cases at least be differentiated from the other 
affections with which it had hitherto been confused. In 1845 von 
Langenbeck of Kiel observed and made drawings of peculiar bodies 
in a case of vertebral caries in man which it is now believed were 
rosettes of the ray fungus. In 1878, Israel demonstrated the disease 
inman. Since that time it has been carefully studied and described 
by a number of investigators. 
Geographical distribution. Actinomycosis is quite widely distrib- 
uted throughout North and South America and Europe. It is much 
more prevalent in certain countries and districts than in others. The 
observation has been made that animals pastured upon low lands and 
in river valleys are more liable to contract it than those feeding upon 
high and dry ground. It has also been noted that cattle fed upon 
rough or coarse forage are more prone to the disease on account of 
abrasions of the buccal mucosa than those kept upon less harsh food. 
It is very difficult to procure reliable statistics concerning the extent 
to which it occurs. The observations which have been made at the 
