308 
GEORGE N. IvINNELL. 
same pasture with comparative impunity. But, further, let 
me illustrate what I say by giving what has been a common 
experience with me in testing diseased herds with tuberculin. 
Let us suppose we have a herd of seventy-five cows in which 
the disease has been in existence four or five years, and let 
us suppose that twenty or twenty-live are diseased. We do 
not find the diseased subjects sprinkled promiscuously 
through the herd, here one and there one. No, we find 
them in clumps and batches, here four or five standing side 
by side, and there, eight or ten stalls further along, another 
batch of four or five more with an occasional isolated case 
between. But let us go further and examine the members 
of each batch individually. On post mortem examination 
we find that almost invariably there is in each batch one 
animal in which the disease is very much more advanced 
than in any of the rest, and the lesions of much longer stand- ; 
ing. Is it not reasonable to say that the case of long stand¬ 
ing is the animal from which the other members of the group 
received their infection ? But the breath and infection from 
this creature were circulating all over the stable in common 
with the breath of all the other animals in it. If the disease 
is so far reaching and infectious, why is it that it did not 
more generally affect the other members of the herd, and 
why so especially those in the immediate vicinity of the ani¬ 
mal worst affected? Of course, in a herd where the disease 
is of very long standing and great extent, as, for instance, when 
eighty or ninety per cent, are diseased, and where healthy 
animals are the exception, this patchy, clumpy feature cannot 
be recognized. 
In September, 1894, at a meeting of the International 
Congress of Hygiene and Domography, held in Budapest, 
Professor Bang, of the Veterinary College in Copenhagen, 
read a paper giving the result of an experiment made at the 
instance and expense ol the Danish Government, by which ^ 
he demonstrated that the spread of the tubei culosis in a 
stable could be prevented by such a simple device as the 
erection of a board partition between the diseased and the 
healthy animals. And it was not an experiment on a small * 
