THE STREPTOTHRICOSES 575 
weeks and we believe that two of our cases may have been 
existent longer than that. It is impossible to estimate the 
duration of the septicemic and gastric forms although 
the latter, judging by the appearance of the ulcers, are 
believed to be chronic. We believe that frequent inspec- 
tion and the precautions as to the character of fodder are 
the only special hygienic measures indicated. 
The Incidence of the Disease. 
Not the least puzzling character of the disease is the 
variability of its appearance. There have been groups 
of cases in our records ; for example the following periods 
showed several while the intervening years lacked them 
entirely— 1905, 1907-8, 1911-2, and 1920-1. The second 
and fourth outbreaks were definitely related to a new 
arrival but the records do not show that such was the 
case for the other two. Mr. Joseph who supplied us with 
many specimens, tells us that he has had an experience 
of fifty-four cases in 200 kangaroos and then failed to 
encounter the disease for years. Perhaps this irregu- 
larity of appearance has something to do with the charac- 
ter of food supplied to the animals. 
Among seventy deaths of Macropodidas we have had 
thirty-three cases of the varieties which I have included 
in this infection, made up of the f ollomng forms ; cases 
limited to the jaws, pharynx and neck, six; cases of this 
sort with extension to lungs and stomach, ten; cases of 
this sort with general spread suggesting septicemia, five; 
gastrointestinal and hepatic, eight; nasal and sinus in- 
fection mthout necrosis in the jaw and with general 
spread including the lungs, four. The total incidence in 
Kangaroos is therefore 47 per cent., the necrotizing forms 
being 30 per cent., the gastrointestinal 11.4 per cent. 
The Pathology, 
The essential features of the necrotizing variety of 
this disease are similar to those of actinomycosis — an in- 
flammation giving rise to much fibrous tissue overgrowth 
