DISPERSAL BY AIR 
i9 
grass, is to raise the hymenial surface well above the sur¬ 
rounding herbage, and thus permit the free passage of air 
over it. 
In the true puff-balls (Lycoperdon) the spores are dis¬ 
persed by air, consequent upon the collapsing or the flaking 
away of the soft inner peridium. The sterile stem-like base 
is firmly fixed to the matrix. The Bovista group of puff¬ 
balls have no such sterile base, and are not firmly rooted. 
At maturity the fungus breaks away from the matrix, and 
rolls long distances before the wind. Lloyd has aptly 
termed them the “ tumblers ” of the puff-ball world. (The 
“ cloud ” emitted by a ripe puff-ball when squeezed consists 
of a multitude of spores. It quickly vanishes as the spores 
separate and float away. If a little of the “ dust ” is puffed 
on to a glass slip and viewed under a microscope with a 
J or | inch objective, the individual spores may be easily 
examined.) 
In many of the sessile species of Peziza the spores are 
also discharged in a “ cloud.” The phenomenon, known as 
“ puffing,” often takes place immediately after the fungus is 
handled or the hymenium is breathed upon. The explana¬ 
tion is that many asci have ruptured simultaneously at their 
apices through expansion or contraction of their walls, and 
emitted their spores with a certain amount of force. 
4. By Animals. — The dispersal of spores by animal 
agencies is a subject of the greatest interest. 
The spores of the familiar Fomes annosus are carried in the 
fur of rabbits and other burrowing mammals, which brush 
against the sporophores often developed on exposed roots of 
fir-trees in the roof of the burrow. The spores of other 
deadly parasites are dispersed in a similar way. 
Truly subterranean fungi, in which complete development 
of the spores takes place beneath the ground, are strong¬ 
smelling only at maturity. The scent attracts mammals, 
which dig them up and eat them with avidity. The well- 
