242 FUNDAMENTALS OF AGRICULTURE. 



food from living hosts, a majority of fungi, known as 

 saprophytes, live upon decaying vegetable or animal 

 matter. Infection of a host takes place when the para- 

 site begins to secure its food from it. 



Reproduction of Fungi. Fungi are reproduced by 

 spores which under favorable conditions develop into 

 new plants similar to the ones producing them, just as 

 seeds of higher plants do. While fungus spores have 

 the same office as seeds, they differ very much from 

 seeds in size, structure and method of formation. 

 Spores are exceedingly small, dust-like particles, and 

 are simple in structure, consisting virtually of a single 

 cell. They are formed in large numbers, sometimes 



SECTION OF POD SHOWING POD SPOT FUNGI. 



on special branches of the mycelium which extend 

 freely in the air; sometimes in minute sunken cavities. 

 Because of their lightness they are readily scattered 

 by the air currents; and insects and water often play 

 a part in their distribution. 



Kinds of Spores. Many fungi produce two kinds 

 of spores at different times and for different purposes. 

 During the period of vigorous growth there are pro- 

 duced, in large numbers, spores that germinate quickly, 

 but that cannot withstand unfavorable conditions; 

 these disseminate the fungus rapidly and extensively 

 during the growing season, and may be called summer 

 spores. As the fungus begins to decline there are 

 formed in smaller numbers spores that will survive 

 exposure to extreme cold or dryness; these carry the 

 fungus over unfavorable periods, particularly the win- 



