JOHNE’S DISEASE 195 
Within the parts which contain large numbers of the bacteria there 
are also sometimes recognizable small round compact nuclei, appar- 
ently belonging to cells of the lymphocyte type, and at their margins 
there are numerous cells whose bodies stain red with Pappenheim’s 
stain. 
The bacteria do not appear to be specially intra-cellular; many of 
them seem to be lying free, and others appear to be situated within 
the fine reticulum of the villi. The structural alterations are every- 
where proportional to the number of bacteria which indicates that, 
contrary to what is the case in tuberculosis, the bacteria have little 
or no tendency to degenerate and disappear from the older lesions. 
The bacteria when numerous are generally arranged in clumps or 
groups, and these often form a very large part of the epithelioid areas. 
The lesions in the lymphatic glands have a similar histology. They 
may be present in either the cortex or the medulla, but they are not 
in the anatomical sense like those of tubercles. A small number of 
giant cells may be present. 
The duration of the disease varies.from a few weeks to several 
months and often a year or more. It seems to be fatal in most cases. 
Diagnosis. Johne’s disease is to be diagnosed by the symptoms, 
lesions, etiology and specific reactions. The diarrhea with the loss of 
flesh and a generally good appetite is very suggestive of this disease. 
The positive diagnosis, however, requires an examination of the 
lesions or the finding of the specific organism. 
Etiology. Meyer found that the bacterioscopic examination of the 
feces and rectal scrapings is of diagnostic value in only about 40 per 
per cent. of cases in the advanced stages of the disease. M’Fadyean, 
Sheather and Edwards diagnosed the disease in 20 per cent. by this 
method. In a total of 15 cases, they made a positive diagnosis in 5 
from rectal scrapings. The difficulty with this method is not restricted 
to the small number of individuals in which it is applicable. It is 
necessary to differentiate the acid-fast bacteria found from those of 
tuberculosis and purely saprophytic forms that may be present. The 
differentiation from tubercle bacteria can be made by guinea-pig 
inoculation. With the development of culture methods the identifica- 
tion of the organism may be simplified. The presence of large num- 
bers of acid-fast bacteria in the feces or in the mucous membrane of 
the intestine is very significant especially if symptoms are present. 
Tuberculin reaction. O. Bang called attention to the value of tuber- 
culin made with the avian variety of tubercle bacteria in diagnosing 
