CHAPTER III. 



MICROBIAL DISEASES OF MAN AND ANIMALS. 

 DISEASES CAUSED BY MOLDS* AND YEASTS. 



The diseases produced by fungi in higher animals are mostly localized 

 infections of the skin (dermatomycoses), of the mouth and throat (thrush), 

 and of the lungs and air passages (pneumo mycoses) . In insects, one large 

 series of forms, the Laboulbeniales, produce local affections only; many 

 other forms from widely different groups are destructive to particular 

 insects. 



PNEUMOMYCOSIS.f 



ASPERGILLOSIS. The fungus diseases of the lungs and air cells of 

 birds is quite uniformly attributed to Aspergillusfumigatus which is widely 

 distributed upon feed and grains as well. The agency of this species in 

 causing disease is well established. It grows best at blood-heat. In- 

 oculation experiments have reproduced the disease. Isolated cases are 

 recorded where the same organism is regarded as the cause of disease in 

 horses or cattle and even man, but not proved. Other species of Asper- 

 gillus, A.flavus, A. nidulans, A. niger, have been listed among pathogenic 

 forms from their presence at times in diseased tissue. Whether these 

 species are ever a primary cause of disease is doubtful. 



Secondary Infections. Spores of any species of fungus found in the 

 locality may find lodgment in wounds, orifices open to the outside, such 

 as the external ear or the air passages. Many of these spores will germi- 

 nate in such situations. If favored by dirt, pus, mucus, or existing 

 pathological condition the resulting growth in some species develops into 

 a secondary infection; most species lack entirely the power to produce 

 disease. The appearance of molds, especially species of Mucor, Peni- 

 cillium, and Aspergillus, in such situations has been frequently reported 

 in literature. In very large measure at least such presence may he re- 



*Arranged genetically as far as possible, 

 f Prepared by Charles Thorn. 



576 



