52 Veterinary Medicine. 



Lesions. These are found in the larynx, trachea, bronchia, 

 lungs, and the air sacs of the soft parts, and less frequently of 

 the bones. The nasal chambers are usually free. They consist 

 of yellowish or greenish membranous patches on the mucosa, or 

 rounded masses like tubercle, and bearing on their surface the 

 mycelial filaments. The masses, which are found also in the 

 diaphragm, liver, peritoneum and intestine, sometimes become 

 caseated or calcified, intensifying the resemblance to tubercle. In 

 pigeons they have been found in the mouth of the size of a pea or 

 bean. The formation consists largely of fibrinous exudate with 

 leucocytes and often cocci or spores, but on the surface the fun- 

 gus growth is easily demonstrated. In the .«olid organs the de- 

 posits may be easily confounded with miliary tubercle, coccidiosis 

 or acariasis caused by the symplectoptes, but under the micro- 

 scope the revelation of the aspergillus filaments and the absence 

 of the parasites which cause these other diseases is diagnostic. 



Pathology. The spore inhaled from the food or dust, and 

 propagating on the mucosa or in solid tissues, interferes mechani- 

 cally with the breathing and other functions and thus establishes 

 its pathogenesis. It leads to local congestion, and exudation and 

 establishes a positive chemiotaxis on the leucocytes, which are 

 seen to accumulate around the growing fungus. Giant cells are 

 often present, so that the histological relation to the tubercle is 

 very close. Fibroid development may also take place in the 

 masses and in these the filaments may disappear. Cultures of the 

 aspergillus, injected into the axillary vein of a pigeon caused a 

 pseudo-tuberculosis of liver and lungs with death in three to four 

 days. Thrown into the trachea they caused death in ten to twenty 

 days, with groups of pseudo-tubercles and numerous caseated 

 centres. 



Yet the aspergillus produces no very actively toxic product as 

 shown by the experimental researches of Schiitz, Kottiar, lyucet 

 and Renon. They have moreover been found on the mucosa in 

 healthy animals, and affected men have recovered when removed 

 from fresh accessions of the spores, so that we may as.sume a 

 power of resistance in healthy tissues, and a special susceptibility 

 in a mucosa weakened by other diseases or by the presence of 

 foreign bodies and other irritants. 



Symptoms in Solipeds. As seen by Schiitz, Rivolta, Martin, 



