546 A MANUAL OF BACTERIOLOGY 



the tongue often protrudes from the mouth, the saliva 

 drips, and the animal becomes much emaciated. 



On cutting into a " wooden tongue," or wen, a grating 

 sensation is felt, such as that experienced in cutting a 

 turnip or unripe pear ; on examining the section little 

 rounded, yellowish, frequently almost caseating, areas 

 will be noticed, resembling old tubercles. In sections 

 examined with a low power, these rounded areas are 

 found to be composed of masses of small round cells, with 

 occasionally giant-cells, surrounded by a capsule of fibrous 

 tissue. The growth may be so soft as to be practically 

 purulent, and abscesses varying in size from a pin's head 

 to that of an orange may be present in the affected areas. 

 Like tubercles, the growths may become caseous, calcified, 

 or fibrous. In the growth or in the pus from abscesses, 

 when examined fresh with a low power, yellowish or 

 yellowish -white granules will be found here and there, 

 which may be very minute, or as large as a small pin's 

 head, are somewhat soft in consistence, and on slight 

 pressure flatten out. Examined with a higher power, these 

 granules are found to contain round, ovoid, or reniform 

 bodies which have a rosette-like outline a more or 

 less structureless centre with club-shaped bodies radially 

 arranged around the periphery (Plate XXI, a). These 

 peculiar structures are the cause of the disease, and are 

 the form assumed in the tissues by an organism known 

 as the " ray fungus," Nocardia bovis (Actinomyces, 

 Streptothrix or Oospora. bovis). 



Sections of the diseased tissues stained by Gram's 

 method with eosin show the structure of the organism 

 still better. Areas of round-celled granuloma are generally 

 enclosed in a well-developed fibrous capsule, and one or 

 more reniform, ovoid or irregular bodies are present in 

 the central portion of the mass. Well-marked club- 

 shaped structures are radially arranged around the 



