FERNS AND MOSSES. 145 
together. It often happens, however, that the chlorophyll is 
disguised by the presence of other colouring matters, as in the 
red and brown seaweeds, which are such familiar objects on 
the seashore. 
Fungi are devoid of chlorophyll, though other pigments are 
commonly present, and they therefore, like certain flowering 
plants, require complex food (pp. 3 and 71). The smallest 
members of this group are the microscopic bacteria (germs or 
microbes) which play a very important part in nature, since 
they appear to be responsible for certain infectious and con- 
tagious diseases, such as cholera, consumption, and typhoid 
fever. They are also the cause of putrefaction and many other 
well-known phenomena, ¢.g., the souring of milk and the 
“ripening” of cheese. Much larger than bacteria, but like 
them unicellular (p. 8) and microscopic, are the spheroidal 
yeast-plants that set up the fermentation by which alcohol is 
produced in solutions containing sugar. Most fungi, however, 
are larger than this and consist of slender threads, which are 
often entangled into a kind of felt-work or even compacted into 
a fairly solid mass. The moulds and mildews common every- 
where are fungi of this sort. They often give rise to diseases 
in plants, such as the notorious ‘‘ potato-disease,” “rust” of 
corn, and ‘“‘ergot”’ of rye. 
The largest and most compact fungi are the familiar puj- 
balls, toadstools, and mushrooms. These consist of an under- 
ground mass of branching threads, the “spawn,” upon which 
grow the conspicuous ‘‘fruit-bodies” that make their appearance 
above ground. Taking a common mushroom as an example of 
such a fruit-body, we find that it consists of a stalk crowned by 
a round expanded cap, on the under side of which are seen 
radiating plates, the “gills,” coloured pink, brown, or black, 
according to the age of the mushroom. It is upon these gills 
that the minute spores are produced, and if a mature mushroom 
is placed on a piece of white paper and covered with a tumbler 
numerous spores will soon be shed on the paper in the form of 
a fine dust. When sections of such fungi are examined under 
the microscope, they are found to consist of fine threads closely 
compacted together. 
BRYOPHYTES include the mosses and liverworts, most of 
which possess stem and leaf although true roots are absent. 
Their life-history presents two stages: one, that of bearing 
spores, and the other, that of the production of egg-cells. 
Any common moss will serve as an example. It is a matter 
of common observation that these plants grow crowded together 
in large numbers, as, for example, on walls. They will often 
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