Il8 STUDY AND IDENTIFICATION OF MOULDS 



i 



THE FUNGI. 



The Thallophyta are plants in which there is no differentiation be- 

 tween root and stem. 



The classes of Thallophyta which are of interest medically are i . the 

 Algae and 2. the Fungi. 



Some include Lichenes as a separate class. These are really sym- 

 biotic organisms 'Fungi parasitic on Algae. 



The Algae contain chlorophyll, with the exception of Cyanophyceae. 

 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 hyphse. 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 which bear the conidia or spores. 



The aerial hypha which carries the fruiting organ encasing the conidia (sporan- 

 gium) is called the sporangiophore and the more or lesg rounded termination of this 

 hypha, which projects into the sporangium, is called the columella. 



The hypha may be composed of one cell or of many cells separated by septa 

 (septate). 



The orders of the class Fungi which are of interest medically are: 

 i. the Phy corny cetes; 2. the A<comycetes; 3. the Hyphomycetes. 



Phycomycetes. These produce a copious network-like mycelium, which is non- 

 septate, and reproduce asexually by means of a sporangium, a case-like structure 

 borne on the clubbed extremity of an erect hypha (columella) and containing numer- 

 ous spores or, as in the case of the suborder Oomycetes, reproduction is by hetero- 

 gamy. (Dissimilar sexual cells a smaller male, antheridium, and a larger female, 

 oogonium. By fertilization by antherozoids from the antheridium penetrating the 

 oosphere we have oospores.) 



The suborder Zygomycetes reproduces either asexually (a sporangium filled with 

 spores) or by isogamy (two similar but sexually differentiated cells conjugate and 

 form on fusion a zygospore). 



Belonging to this suborder we have four families, only one of which, the Mucor 

 family, is of importance medically. In this family we have three genera: Mucor, 

 without rhizoids; Rhizopus, with rhizoids and unbranched aerial hyphae and, 

 Rhizomucor, with rhizoids and ramified mycelium. 



Two species of Mucor are of pathogenic importance. 



i. Mucor mucedo and 2. Mucor corymbifer. These moulds develop especially 

 in external cavities as nasopharynx and external ear. 



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 fructifica- 



