TUBERCULOSIS 379 



are more plentiful and more easily demonstrated than in 

 older and more chronic ones. They tend to be more 

 numerous in some animals than in others in the ox and 

 horse than in man, for example. In man the bacillus is 

 frequently difficult to demonstrate (by staining) in en- 

 larged and caseating glands, in pus, in synovial membranes 

 and particularly in lupus. In some animals, especially 

 the ox and horse, bacilli can usually be readily demon- 

 strated, and may be present in large numbers, and fre- 

 quently have the typical distribution, viz. within and 

 at the periphery of the giant-cells, though they are by 

 no means confined to this locality (Plate X, 6). The 

 bacilli are comparatively scanty in the lesions in guinea- 

 pigs. 



In the ox the tuberculous lesions are most frequently 

 met with in the lymphatic glands and serous membranes, 

 particularly the pleura, and in the lungs and liver, while 

 the fat and muscular tissues, which constitute the major 

 part of " meat," are very rarely affected. On the pleura 

 the growths take the form of nodular masses, which from 

 their arrangement are popularly termed " grapes " or 

 " angle berries," the " perlsucht " of the Germans. 



In carp, tubercle-like nodules are occasionally met with 

 in which a bacillus resembling the tubercle bacillus in 

 morphology and staining reactions is present. It grows, 

 however, much more freely than the mammalian tubercle 

 bacillus, and though inoculable into fish and frogs, is non- 

 inoculable into warm-blooded animals. It is said to yield 

 a tuberculin which reacts with mammalian tuberculosis ; 

 but this is dubious, and Calmette l states that the piscian 

 acid-fast bacillus is distinct from the mammalian and 

 avian tubercle bacilli. 



Bird or avian tuberculosis differs in many respects 

 from mammalian tuberculosis. The tuberculous new 



* ' Infection Bwillairt et la Tubercwkse, 1920, 



