YEASTS AND MOLDS 223 



as coccidia and sporozoa, are yeasts. These are, however, 

 protozoa. 



Blastomycetic Dermatitis or Oidiomycosis. A skin 

 disease described, in 1894, by Gilchrist, and since then by 

 other writers, is due to a fungus which resembles yeast, and 

 which has been called a blastomyces; but Ophiils and Ricketts 

 term it an oidium, and the former calls the parasite O'idium 

 coccidioides . 



On Loffler's blood-serum and agar a growth occurs in from 

 three to seven days, small white colonies made up of branch- 

 ing, mold-like forms. On potato the growth is more rapid and 

 shows the yeast forms. 



The disease is slow in process, ten to twelve years, 

 leaving much deformity. When generalized, it is fatal. 



Form. The fungus increases by budding, but in culture- 

 media it may resemble a mold or oidium. 



Pathogenesis. Small abscesses form in wart-like lesions, 

 which extend over large areas of the skin, becoming later 

 on systemic and invading lungs and kidneys; abscesses and 

 nodules form in these organs. 



Hyphomycetes (True Molds). Fliigge has made five 

 distinct divisions of molds. It will, however, serve our 

 purpose to classify those to be described under three head- 

 ings: Penicillium, Mucor, and Aspergillus. 



Penicillium Glaucum. Origin. The most widely dis- 

 tributed of all molds, found wherever molds can exist. 



Molds frequently contaminate the cultures by bacteria and 

 culture-media. 



Form. From the mycelium, hyphae spring which divide 

 into basidia (branches), from which tiny filaments arise 

 (sterigmata) , arranged like a brush or tuft. On each sterigma 

 a little bead or conidium forms, which is the spore. In this 

 particular fungus the spores in mass appear green. 



Growth. It develops only at ordinary temperatures, form- 

 ing thick, grayish-green molds on bread-mash. At first these 

 appear white, but as soon as- the spores form, the green pre- 

 dominates. Gelatin is liquefied by it. 



