30 ELEMENTARY BIOLOGY. [v. 



other, and far larger, series present chlorophyll, and have 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, a kind of cells, 

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

 structure, are essentially similar to Torulce. Indirectly or 

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

 is termed a hypha, and out of these hyphaB 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 detached 

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

 this lies a felt- work of delicate tubular filaments, the hyphse, 

 forming a crust like so much blotting-paper, which is the 

 'mycelium. From the free surface of the crust innumerable 

 hyphaB 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 

 hyphse, 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, multitudes of 

 silvery hyphse will be seen radiating from its periphery and 

 giving off many submerged, but few or no vertical, or sub- 

 aerial, branches. Submitted to microscopic ' examination, a 

 hypha is seen to be composed of a transparent wall (which 

 has the same characters as the cell-wall of Torula) and proto- 

 plasmic contents, which fill the tube formed by the wall, and 

 present large central clear spaces, or vacuoles. At intervals, 



