SCATTERING OF SPORES 37 



water. Water is absolutely necessary for the first kind. 

 Some swimming spores are known to find their way from 

 plant to plant through the water in the soil itself, 

 especially soon after rain or heavy dew. This is true of 

 the fungus causing the "damping-off" of seedlings. Many 

 parasitic plants that attack seed plants exude their spores 

 in moist weather, and rains wash them down from the 

 leaves and bark. Thus they are carried to new parts of 

 the same plant, or to other plants, by first infecting the 

 soil about them. 



7. Spores Carried by Insects, Birds, etc. A number of 

 fungi attack fruits, seeds, leaves, and other parts of plants. 

 Insects and birds may use these for foods. These animals 

 carry spores of these fungi from an infected to an 

 uninfected plant, very much as they carry pollen from 

 flower to flower. The spores adhere to the feet and to the 

 mouth parts particularly, and these are the parts most 

 likely to bring them in contact with fresh surfaces. 

 Furthermore, insects may feed directly on the fungi and 

 necessarily carry away spores and distribute them widely. 



8. Spores Disseminated by Man. Man, in his mastery 

 of the earth and in his exchange of its products, is sure 

 to distribute spores. Soil spores are carried far and wide 

 by plowing and harrowing, by tools and wheels of 

 vehicles, and by the transportation of soils and manures. 

 The shipment of infected nursery stock, seeds, and fruits 

 is responsible for the wide distribution of the spores of 

 many fungi that attack plants. Similarly, the shipping of 

 hay, grain, vegetables, and any of the raw food products 

 tends to spread any spores that are on these plants. 

 Certain kinds of fungi have thus followed man very 

 closely in his movements around the earth. 



