BOVINE TUBERCULOSIS. 
361 
appearance, however, certain “ morphological differences are 
found,” and “ under different circumstances and within limits, 
the morphology of the tubercle bacilli varies with its environ¬ 
ments.” Thus tubercle bacilli from the nodulus of “ perl- 
sucht ” are generally shorter and thicker than those from the 
human being. Those found in cows’ milk again approach 
more nearly to the familiar rod-shaped bacilli found in the 
human sputa; but while minute morphological differences 
can be detected in the tubercle bacilli of different species of 
animals, the general characters and characteristics of staining 
and culture are the same in them all. 
In considering the aetiology of bovine tuberculosis, there 
are two natural groupings into which the methods of infec¬ 
tion can be divided. The first and most important is by the 
introduction of the bacilli through the respiratory tract. The 
second, the direct introduction of the germ through congeni¬ 
tal or hereditary transmission, or through eating or drinking 
tuberculous meat or milk. 
In considering the first group it is necessary to take a 
generally broad view of the subject, and include all sources 
from which the tubercle bacilli can gain access to the atmos¬ 
phere, whether that source is a consumptive human being or 
a tubercular cow matters not. Once they gain entrance to 
the atmosphere, from whatever source they come, they are 
equally dangerous. 
The two most important means by which the bacilli can 
gain admittance to the atmosphere are: Fist, by the expec¬ 
torations ol consumptives. Second, by the nasal discharge 
of diseased animals. 
In reviewing the work on the subject of phthisical expec¬ 
torations, in the Manual of Medical Science for 1890, Whit¬ 
aker says : 
“ The work of the year has established almost to universal 
conviction that pulmonary tuberculosis is caused exclusively 
by inhalation of dried sputum. This, the original postula of 
Koch, met its conclusive proof in the studies o l Cornet. ‘ It 
is not,’ he says, ‘ the breath of the consumptive which is 
dangerous, but singly and alone the inhalation of the dried 
