CHAPTER XVIII 



MOULD-FUNGI : HYPHOMYCETES OR MYCELIAL FUNGI 



Of this class of fungi only those are of special interest to 

 -the pathologist which in some way or other are connected 

 with disease. The fungi consist of branched and septate 

 threads or hyphffi ; each filameiit or hypha is composed of a 

 row of cylindrical cells, consisting of a membrane and clear 

 protoplasm, the individual cells being separated from one 

 another by a thin transverse septum ; they increase in 

 number by fission, and in this way the filaments increase in 

 length. The growing ends of the hyphae are filled, not with 

 transparent, but with highly-refractive protoplasm. Some 

 cells, by budding out laterally, produce cylindrical threads, 

 which subdivide into a series of cylindrical cells, these by 

 division and lengthening forming a new branch-hypha. The 

 filaments form by their branches an interlacing feltwork, 

 called thallus or mycelium. The mycelial fungi which in- 

 terest us belong to the order known to botanists as the 

 Ascomycetes. They are characterised by the fact that one or 

 other branch of the mycelial hyphae produces at its end a 

 series of spherical or oval cells — the conidia spores or con- 

 idia. In addition to this some of the hyphce form peculiar 

 large mother-cells, or sporangia, in the interior of which 



