2 
DEVELOPMENT 
of the latter, but differ from both in the entire absence of 
chlorophyll, or green colouring matter. Lacking chlorophyll, 
they require organic matter for food, hence flourish as sapro¬ 
phytes on dead organic matter, and as parasites on living 
organic matter, either plant or animal. They absorb oxygen 
and give off carbon dioxide, in this respect resembling 
animals. The curious aberrant group known as the 
Mycetozoa, or fungus-animals, occupy an anomalous position 
between the animal and vegetable kingdoms. They ap¬ 
proximate more nearly to plants, and at one time found a 
place in our fungus textbooks. 
A fungus is best defined by negative characters. Chloro¬ 
phyll, as already remarked, is never present; also, there is 
no system of true tissues. The latter are replaced by 
threads (hyphse), which do not fuse organically in a lateral 
direction, but intertwine instead. These characters must 
occur simultaneously, otherwise the plant is not a fungus. 
The importance of this is easily recognised if it be remem¬ 
bered that chlorophyll is absent from some parasitic 
flowering plants, and that certain algae consist only of 
thread-like bodies ; but the rank of the former is at once 
indicated by the system of connective tissues, and of the 
latter by the presence of green colouring matter.* 
It seems hardly necessary to remark that a fungus, no 
matter where it occurs, is not a de novo production. It is 
the outcome of a spore (or spores), analogous to a seed in 
the higher plants, produced by a fungus of the same species, 
which, finding itself upon a suitable matrix, germinated and 
reproduced its kind. If spontaneous generation is a fact, as 
* Fungi are of great antiquity. Over 400 fossil species have been 
described. They have been observed in vegetable tissue from rocks of 
the Carboniferous Age—in some cases so well preserved that details of 
structure, and even spores, have been made out. These early fungi 
are chiefly Ascomycetes; gilled and tube-bearing forms have been found 
in Tertiary strata. 
