488 DISEASE IN WILD MAMMALS AND BIRDS 
decision that one or the other route has been taken may be 
erroneous, and statistics therefore can often be fallacious. 
It is usually the rule to assume that the oldest or best 
developed lesions occur where the originally settled 
organisms exerted their maximum effect. The questions 
of infection-path and of' original lesion not having been 
settled it is obvious that decision as to the route must be 
in the nature of an estimate. With these limitations in 
mind I have divided the cases into probable respiratory 
and alimentary origins according to the following criteria. 
Where the lesions were wholly respiratory or within the 
lymph glands of the trachea and bronchi the decision was 
not so diflficult. Predominance of the pulmonary disease 
with recent lesions in other organs was taken to indicate 
an aerogenic origin. The chronic ulcerative or fibrous 
pulmonar^^ lesions were also ascribed to those beginning 
in the lungs. The alimentary tract was considered for 
this purpose as beginning in the tonsillar area and ending 
at the anus. This is as I understand the customary teach- 
ing. When the lymph nodes of the alimentary area were 
advanced in the process, the intestinal method was held 
responsible. It is of course not to be forgotten that 
organisms coughed up from the lungs and swallowed may 
be responsible for lesions within the alimentary system. 
However, a predominance of intestinal, splenic, hepatic 
and lymphatic lesions caused me to place the case with 
those originating from the alimentary tract. Granting 
the limitations of our knowledge, of the criteria and of my 
ovm judgment, it is noteworthy that the results of this 
division of the table are not contradictory to the usual 
teaching, the most conspicuous being the predominance of 
the alimentary infection of Aves and in the order 
Primates, whereas the pulmonary route has the highest 
figures for the Ungulata. 
The next subdivision of the table concerns the gross 
pathological type. Beginning with the most acute form, 
the acute miliary, progression is made in terms of 
