XIV] BACILLUS TUBERCULOSIS 339 



tubercle virus, and must therefore be considered as not free 

 from danger. 



In guinea-pigs, rabbits, and fowls, in all tubercular de- 

 posits giant cells are numerously met with. 



Bovine TuBERcaLosis 



Tuberculosis is a common disease of the bovine species : 

 the number of tubercular animals is astonishingly great. In 



Fig. 131. — From a Preparation of Caseous Matter from Pulmonary 

 Deposits in Bovine Tuberculosis, stained as in preceding figure. 



Magnifying power 700. 



many instances, on slaughtering them, only the lungs 

 are found diseased, presenting a peculiar and characteristic 

 appearance, viz., the surface of the lung, of the pleura and 

 diaphragm presenting numerous oval, spherical or irregular 

 shaped nodules, some with short broad basis, others with 

 long thin basis or stalk fixed on to the organs, sometimes 

 clusters of them projecting from the general surface ; these 

 appearances have caused the disease to be called "the 

 grapes," in German " Perlsucht." Not only the surface of 

 the lung, but also the interior contains numerous such 

 nodular deposits. They differ considerably in size, some 



z 2 



