100 STUDY AND IDENTIFICATION OF MOULDS. 



Some include Lichenes as a separate class. These are really 

 symbiotic organisms Fungi parasitic on Algae. 



The Algae contain chlorophyll, with the exception of Cyanophy- 

 ceae. To the order Cyanophyceae it is considered that the family of 

 Bacteria belong. 



The fungi do not possess chlorophyll. They are in their simplest 

 forms ramifying filaments called hyphae. The vegetative hyphae 

 which intertwine in tangled threads, as a support, are termed the 

 mycelium, while those which project upward are called the aerial 

 hyphae and are the ones w r hich bear the conidia or spores. 



The orders of the class fungi which are of interest medically are: (i) 

 the Phycomycetes; (2) the Ascomycetes; (3) the Hyphomycetes. 



Phycomycetes. These produce a copious mycelium, bear conidia, 

 and reproduce in the case of the suborder Oomycetes by heterogamy. 

 (Dissimilar sexual cells a smaller male, antheridium, and a larger 

 female, oogonium. By fertilization by antherozoids from the anther- 

 idium penetrating the oosphere we have oospores.) 



The suborder Zygomycetes reproduces either asexually or by 

 isogamy (two similar sexual cells conjugate and form on fusion a 

 Zygospore.) Of these w r e have two species of the genus Mucor: (i) 

 Mucor mucedo and (2) Mucor corymbifer. These moulds develop 

 especially in external cavities. Pulmonary and generalized infections 

 have also been reported. The pathogenic species have smaller spores 

 and grow best at 37 C. The thick, coarse, cotton-like mould seen on 

 horse manure is a Mucor. The sporangium, the organ of fructification, 

 contains the spores within its interior. The M. mucedo has thick 

 silver-gray mycelium, with large sporangia, 150/4 in diameter, contain- 

 ing oval spores, 5 x 9/4. The M. corymbifer, which has been re- 

 ported from a generalized infection, considered as typhoid, shows a 

 snow-white mycelium. The sporangia are 20 to 40/4 and the spore 

 about 3/z in diameter. 



Ascomycetes. In this order are included many of the parasitic 

 moulds. The most distinctive characteristic is the formation of 

 ascospores in an ascus (little sac). It is an elongated sporangium in 

 which a definite number of spores, usually eight, is formed. The 

 ascus usually ruptures at its tip. Other members of the order are 



