21 8 PA THOGENIC MICROORGANISMS. 



the phycomycetes. The latter, besides being distinguished by 

 their lack of partitions between the mycelia, have the power 

 of sexual reproduction. This is accomplished by neighboring 

 hyphce throwing out lateral branches called gametophores, 

 which meet, with free intermingling of their protoplasm. 

 Soon an independent cell is formed at their junction, from 

 which an ordinary branch is thrown out, gradually forming at 

 the tip an asexual sporangium. 



The moulds are responsible for various skin diseases which 

 will be briefly mentioned. 



Thrush is caused by the o'idium albicans (oi'dium, a form of 

 fungus between the yeasts and moulds, possessing some of the 

 characteristics of both). 



Langenbeck, in 1839, described the oidium albicans, which 

 consist of budding cells resembling tho.se of yeasts. They 

 are 10 to 20 v in diameter and sometimes produce mycelia. 

 They grow on all culture-media and stain with all ordinary 

 aniline dyes. Some types liquefy gelatin. 



Pathogenesis. In cases of malnutrition, especially with un- 

 clean surroundings, o'idium albicans is able to cause an in- 

 flammation of the tongue and mouth. This inflammation is 

 attended by the formation of pearly white slightly elevated 

 translucent spots, which tend to spread quickly and may 

 coalesce. 



Ringworm. Tinea circinata, Trichophyton tonsurans. 



History. The credit of the discovery of these moulds as 

 the cause of ringworm belongs to Gruby, who, in 1849, de- 

 scribed these tricophyta. 



Morphology and Staining. They consist of mycelia in great 

 numbers with enclosed spores. Staining is easy, but not 

 needed. For examination a hair-bulb should be plucked out 

 and examined in a solution of caustic potash. 



Biologic Character. Tricophyton tonsurans grows on all 

 ordinary culture-media." Gelatin is liquefied. 



Pathogenesis. In man ringworm of the scalp and body are 

 produced by contact with infected individuals or the use of 

 infected articles. Domestic animals may become infected, 

 and constitute sources of infection. The disease consists 



