2l6 
THE PLANT WORLD. 
Then place it in a tumbler with a little moist paper in the bottom 
and cover with a piece of glass to keep the air in the tumbler 
moist. In a few days several molds will probably be growing on 
it. If there is a black one it is probably the black mold desired. 
Place some pieces of stale bread in a pan with some moist paper 
in the bottom, moisten the bread slightly and with a needle or 
small instrument plant some of the black spores from the orange 
or lemon on the bread. Cover the pan with a glass or another 
pan. 
In a few days note the white mold growing over the bread. 
With a hand or pocket lens examine this and observe that it con¬ 
sists of very delicate, branched, white threads. This is the 
mycelium of the fungus. Nearly all fungi (except some of the 
very low ones, and some very specialized forms) have a mycelium. 
It is the vegetative or growing part of the fungus as contrasted 
with the fruiting parts. 
In a few days, the fungus will become black. This is due to 
the development of numerous, dark, rounded and very minute 
bodies called spores, which are formed in a round spore case 
(sporangium). These spore cases are very numerous and are 
formed on the end of erect fruiting branches of the mycelium. 
When the culture is quite old the fungus is apt to grow off from 
the bread onto the sides of the pan. Now with the hand lens 
examine the spore cases and the fruiting branches of the mycelium 
where they are on the sides of the pan. Note that several of 
these fruiting branches, each bearing a spore case, arise in a 
cluster from the same point. Probably at the base of the fruit¬ 
ing branches a cluster of minute dark “ rootlets ” will be seen. 
By noting carefully it will be seen that a “ runner ” or single 
thread extends from this cluster a short distance to where another 
cluster is formed, and then on to another, and so on. In this 
way the fungus extends itself over the sides of the pan, or other 
substratum on which it is growing, somewhat as a strawberry 
“ runner/’ or the “ walking ” fern, travels over the ground. 
The spores in the spore case are easily set free, and are carried 
in currents of air to other places where they start more mycelium. 
