68 JOHNE^S DISEASE 



immediately on to all the ordinary laboratory media. 



In our experiments the diseased tissue was placed 



either directly on to the medium to be tested or after 



previous treatment with a i per cent, watery solution 



of ericolin to kill contaminating micro-organisms. The 



method of making direct cultures was as follows : 



The gut and glands were thoroughly washed with 



water, and the surface of an infected area seared with 



a hot spatula ; microscopic films were made from the 



tissues beneath the part seared to prove the presence 



of the specific bacillus. Small pieces of tissue were 



then removed with sterile scissors and rubbed over the 



surface of the culture medium to be tested. If the 



tissues were contaminated, the indirect method of 



cultivation was adopted — i.e.^ the tissue was previously 



placed in a sterile i per cent, watery solution of 



ericolin and heated for an hour at 37° C, after which 



the particles of tissue were removed and rubbed over 



the media to be tested. The ericolin was used to kill 



off most of the contaminating micro-organisms, for, as 



has already been pointed out by one of us (F. W. T.), 



the acid-fast group of bacilli are but little affected by 



the action of this substance. 



In the first instance we used as media unheated 

 extracts and tissues of normal cattle. The fresh 

 extracts of glands and organs, including the intestines, 

 were made and sterilized by passing through a 

 porcelain filter. These extracts were placed in sterile 

 tubes, and each was tested as a medium per se, and 

 also added in various proportions to the ordinary 

 laboratory media. Small sterile portions of bovine 

 organs, especially lymphatic glands, were also obtained 

 and placed in sterile tubes. All these media were 

 tested in various combinations, with and without 

 glycerine, cholesterine, various sugars, fresh blood, 



