560 
A. 0. ZWICK. 
of original investigators who- can be called upon to verify the 
statement that food infection, through meat and dairy products, 
in all probability constitutes by far the greatest cause of even 
pulmonary consumption. For proof of this we need only refer 
to the excellent summary of this subject contained in the United 
States Government report, issued by M. J. Rosenau, Director of 
the Hygienic Laboratory, Bulletin No. 56, on milk and its rela¬ 
tions to the public health, in March, 1909, beginning page 540, 
under the caption, “ The Virulence and Vitality of Tubercle Ba¬ 
cilli in Dairy Products.” 
Attention is here called to the fact that the inhalation theory, 
to account for the frequent presence of tuberculosis in the pul¬ 
monary tissues has not been proven, and that living tubercle ba¬ 
cilli in dust are hard to find or could not be found at all, sputum 
in fact being very hard to pulverize, and sunlight very easily kill¬ 
ing the germs in a few minutes (five to ten) in the translucent 
material. 
On the differences between types of bacilli of the same spe¬ 
cies, depending on hosts and environments, I have already dwelt 
sufficiently: Theobald Smith’s work can also be quoted in proof 
of the fact that these distinctions are only seeming, as far as 
constituting entirely different organisms are concerned, that as 
a matter of fact the tubercle bacillus includes so many different 
types that their extremes would leave us in doubt as to their 
specific classification if they were not connected by a chain of 
forms of transition. 
Mohler and Washburn even conclude, after a comparison of 
many tubercle bacilli from different sources and careful search 
of the literature, “ that the more the subject is studied the more 
numerous the instances become in which bacilli of different spe¬ 
cial types are found occurring naturally in animals far removed 
from the species which was supposed to be their natural host.” 
We can find nothing in their work to encourage us to undervalue 
the importance of those from bovine sources as a menace to the 
public health. 
Fibiger and Jensen, among thirty-nine cases of primary tuber- 
