416 ELEMENTARY BIOLOGY. [CHAP. 



and has the physiological peculiarities of Protococcus. The 

 former series comprises the Fungi, the latter all other plants, 

 only a few parasitic forms among these being devoid of 

 chlorophyll. 



The Fungi take their origin in spores t a kind of cells, 

 which, however much they may vary in the details of their 

 structure, are essentially similar to Tortda. Indirectly or 

 directly, the spore gives rise to a long tubular filament, 

 which is termed a hypha, and out of these hyphae the 

 Fungus is built up. 



One of the commonest Moulds, the Penicillium glaucum^ 

 which is familiar to every one from its forming sage-green 

 crusts upon bread, jam, old boots, &c. affords an excellent 

 and easily studied example of a Fungus. When examined 

 with a magnifying glass, the green appearance is seen to be 

 due, in great measure, to a very fine powder which is de- 

 tached from the surface of the mould by the slightest touch. 

 Beneath this lies a felt-work of delicate tubular filaments, 

 the hyphae, forming a crust like so much blotting-paper, 

 which is the mycelium* From the free surface of the crust 

 innumerable hyphae project into the air and bear the green 

 powder. These are the aerial hyphce. On the other hand, 

 the attached surface gives rise to a like multitude of longer 

 branched hyphae, which project into the fluid in which the 

 crust is growing, like so many roots, and may be called the 

 submerged hyphce. If the patch of Penicillium has but a 

 small extent relatively to the surface on which it lies, mul- 

 titudes of silvery hyphae will be seen radiating from its 

 periphery and giving off many submerged, but few or no 

 vertical, or subaerial branches. Submitted to microscopic 

 examination, a hypha is seen to be composed of a transpa- 

 rent wall (which has the same characters as the cell-wall of 

 Torula] and protoplasmic contents, which fill the tube 



