REPRODUCTION BY SPORES 35 



are not motile and are lighter than water, they may float 

 at the surface and be carried long distances by the 

 currents. 



The spores of the majority of the fungi, however, are 

 adapted to the air. They are set free as a dry powdery 

 mass. You doubtless have seen the dense powder arise 

 from a broken puff-ball. This is made up of the thousands 

 of spores which it forms. They have coats which prevent 

 too great loss of their moisture by evaporation, are not 

 actively alive while in the atmosphere, have no motion of 

 their own, and are a little heavier than air, so that in 

 still air they settle to the earth. When the air is in 

 motion, however, they are carried far and wide. They 

 may be dropped temporarily, but unless they fall in a 

 moist place suitable for their germination so that they 

 take hold on the solids, they are readily picked up again 

 and carried on. It is perfectly safe to say that spores 

 may be carried hundreds of miles in times of high winds. 



4. The Special Methods of Scattering Spores. The 



following classification of the methods by which spores 

 are scattered will enable the student to see the variety. 

 Some of these methods are more effective than others, 

 but the sum of all is to make plants very widely 

 distributed. 



A. Spores carried by the air. 



1. Without any aid from the plant itself, such as 

 a projection of the spores into the air by some 

 explosive act. 



2. Spores driven to some distance from the parent 

 plant by the presence of some explosive change 

 in the plant itself. 



B. Spores carried by water. 



1. Spores are passively carried by currents of water. 



2. In addition to the water currents, some spores 

 have a power of motion of their own. 



