232 FARM FRIENDS AND FARM FOES 



wet with dew or rain, it sends out a germinating tube that 

 penetrates the outer skin, generally through a breathing 

 pore, and' starts a growth of fungus threads or mycelium 

 inside. These threads continue to grow and push in be- 

 tween the green cells of the leaf or stem, absorbing nourish- 

 ment from them. 



After a short time the early spring mycelium has absorbed 

 so much material from the green cells that it is able to de- 

 velop a new set of spores. A special growth of the fungus 

 threads occurs at certain places just below the outer skin. 



Spore GERMiNATrNG with Tube Germinating Tube among 



ENTERING SfOMATA; SEEN CELLS OF LEAF; SEEN FROM 



FROM ABOVE SIDE 



which becomes swollen with light green spots. Soon the 

 skin breaks apart and the fungus threads produce great 

 numbers of small round spores. The small swollen places 

 where these spores are produced are called cecidia (singular, 

 cecidiuni), and the spores produced in them are called CBcid- 

 «fl/- spores or spring spores, because they develop in spring. 

 These spring spores are scattered broadcast by the wind. 

 When one of them chances to alight upon the green surface 

 of a moist asparagus plant, it sends out a germinating tube 

 that penetrates- the tissues in much the same way that the 

 germinating tube of the sporidium did at the beginning of 

 the season. On the inside the germinating tube continues 

 to grow, forming new fungus threads that absorb the life 



