DISEASES OF THE OX AND SHEEP, 



218 



and so produce tuberculosis in animals subjected to it. Koch 

 cultivated the bacilli outside the body, and by dint of great care 

 succeeded in isolating them. The bacilli thus obtained, when 

 inoculated into suitable animals, always produced tuberculosis. 



If these bacilli are inj ected into the tissue under the skin, or 

 into the peritoneal or pleural cavity of guinea-pigs and rabbits, 

 there will be produced after three, four, or more, weeks, a swell- 

 ing of the lymphatic glands near the seat of the inoculation, 

 and these glands will subsequently caseate and ulcerate, just as 





Fig. 21. 



The above picture is a representation of the microscopic appearance presented 

 by a section of a portion of the kidney of a rabbit which died from the effects 

 of Artificial Tuberculosis, (a) Blood-vessel filled with caseous matter, and in 

 it numerous tubercle-bacilli. (6) Nuclei of cells of the tuberculous new 

 growth, (c) Capillary vessel cut transversely across its lunjen, Magnifying 

 power 700. After Klein. 



they would do, if they were affected with the disease in any other 

 way. The spleen also is enlarged by the growth of numerous 

 tubercles. The liver also is seen to be mottled by whitish 

 points and streaks, which afterwards merge and become caseous. 

 The peritoneum and bronchial glands are also attacked, and 

 the lungs show isolated tubercles which are at first grey and 

 transparent, and then become caseous in the centre. 



It has been suggested that if the germs of typhoid fever are 

 inhaled, from drain-pipes or otherwise, the disturbance set up 

 commences in the lungs, while if the source of mischief has 

 entered the system by being swallowed, the first signs of the 



