Parasites of the Air Passages and Lungs of Birds. 395 



smoky aspect, by its yellowish or bluish sterigmata, becoming 

 brown or dark gray, and by the head of smooth, rounded, color- 

 less conidia. 



2. A. Nigrescens, Black A., (Nigrescens black), occurs in 

 clumps of a brownish black, with sterigmata long, brown and 

 toward their summits branched, bearing brownish or brownish 

 violet heads and conidia. 



3. A. Glaucus, Green A., (Glaucus sea-green). Sterigmata 

 yi inch in length, with irregularly globular heads, greenish blue, 

 yellow or brown, bearing grayish green conidia. 



4. A. Candidus, White A., (Candidus lily white). Has 

 transparent sterigmata, with truncated heads, and colorless coni- 

 dia — snowy white when seen in mass. 



The A. glaucus and A. candidus vegetate at a low temperature 

 only and are not liable to colonize the interior of the respiratory 

 organs. The same is in a measure true of A. Nigrescens which 

 does not vegetate above 35° C. (Schiitz), and though it may 

 grow, it fails to produce a mycelium in the body of the bird. A. 

 fumigatus, which vegetates at 37" to 40° C. (Schiitz), is there- 

 fore incomparably the most dangerous. 



Lesions in Birds. These are usually concentrated in the 

 trachea, bronchia, lungs and the various air-sacs in soft tissues : 

 they are less common in the air-sacs in the bones including the 

 nasal chambers. They are in the form of round, or disc-shaped 

 masses about i cm. in diameter or less, of a dull yellow hue often 

 shaded with green, and often presenting the histological structure, 

 as well as the form of a tubercle. Small lymphoid and giant cells 

 are in evidence, surrounding a central mycelium or spores. 

 Ivike as in tubercle, caseous degeneration is the rule and calcareous 

 change is not uncommon so that they are very liable to be mis- 

 taken for tubercles. The lung tissue around the pseudo-tubercles 

 is usually congested and hepatized. Another affection with which 

 they are liable to be confounded is acariasis from symplectoptes 

 cysticola (Perroncito). To the naked eye the nodular lesions, 

 caseation and calcification, are identical. Fibroid degeneration is 

 also seen in certain cases. 



The differential diagnosis is to be made by the microscopic 

 recognition of the mycelium and spores in the centre of the case- 

 ous mass. The hard nodule or, in the older cases, the caseous 



