472 A MANUAL OF BACTERIOLOGY 



globular masses, the spores, are formed ; this process is repeated 

 until a chain of spores results, the proximal one being the youngest. 

 A spore when placed under favourable conditions germinates, a little 

 bud appearing, elongating, and forming a hypha, just as in Mucor. 

 Brefeld, by sowing spores on moist bread, inverting the bread, 

 and examining at intervals, observed a sexual method of repro- 

 duction in Penicillium. Two sets of spiral cells develop on a thick 

 hypha, they intertwine, their contents probably mingle, and from 

 the union or carpogonium a tube-like hypha develops, which 

 becomes surrounded and enclosed by branching hyphse from the 

 mother cell. By further development and thickening of the cell- 

 walls a sclerotium forms ; it is a hard solid body, yellowish in colour, 

 and resembles a grain of sand, the carpogonium being at the centre. 

 If placed in favourable conditions the sclerotia germinate after some 

 time. Two forms of hyphse are produced, one thick, the other 

 thin ; the latter become much twisted. The thick hyphce become 

 branched, and ultimately a number of pear-shaped bodies are pro- 

 duced. The contents of these bodies then become broken up and 

 form spores ; the bodies are known as asci and the spores as asco- 

 spores. From the ascospores the ordinary mycelial form again 

 develops. 1 



Aspergillus niger 



Aspergillus also belongs to the Ascomycetes, and representatives 

 of this genus are common on damp and decaying vegetable matter. 

 The asci occur as golden-yellow bodies in the mycelium. It forms 

 conidiophores which are unbranched and are swollen at the tip. 

 Short unbranched stalks (sterigmata) grow on this swelling and on 

 the tips ot these the spores develop. A process of sexual reproduc- 

 tion occurs very like the one observed in Penicillium. Aspergillus 

 niger grows well on the ordinary laboratory media, producing on 

 potato a powdery, sooty growth after a time. Aspergillus gla.ucus 

 is a common green-spored species. 



With the exception of the ringworm and allied fungi, 

 which produce parasitic skin affections, the Hyphomycetes 

 are not of very great pathological importance. In the 

 ear and nose mucors and aspergilli may be met with, but 

 in these situations they are epiphytes rather than parasites, 

 and the same species occur in bronchiectases and pulmonary 



1 See Brefeld, Quart. Journ. Microscop. Soc., vol. xv, p. 342. 



