60 JOHNE'S DISEASE 



erroneous conception of the original pathological 

 condition. 



The congested vessels of the intestines may take up 

 quite a large proportion of the microscopic field ; not 

 only is this so of the submucosa, but also, to a less 

 extent, of the mucous layer. The rest of the organs, 

 with the exception of the liver, appear to be free from 

 bacilli and histo-pathological lesions. In some cases 

 the liver has presented a fatty appearance; but in 

 naturally affected cases we have never been able to 

 find bacilli in this situation, and the condition does 

 not appear to have been recorded by other workers, 

 except by M'Fadyean, Sheather, and Edwards in one 

 cow, and by Stockman, who noted it in an affected 

 sheep. In this connection, the effect of Johne's 

 bacillus on the liver of rabbits, which is described in 

 Chapter IX., is interesting. 



The histo-pathological changes found in the in- 

 testines of sheep are more or less identical with those 

 found in bovines. In 1908 Vukovic found cases of 

 Johne's disease in sheep in Bosnia, and he was kind 

 enough to send us a paraffin block of the intestine of 

 one of these animals. Very large numbers of acid-fast 

 bacilli were found, the majority being situated in the 

 villi. The general condition of the intestine was 

 similar to that described above in the cases reported 

 by Stockman and by M'Fadyean. 



In our experimentally inoculated sheep the liver 

 showed a small round-celled infiltration, and the gland 

 cells of the organ stained badly. 



From what has been said it is clear that the patho- 

 logical condition caused by Johne's bacillus is strilcingly 

 different from that found in tubercular disease that has 

 existed for any length of time, although, as M'Fadyean 

 points out, the disease in the early stages is really very 



