PLANTS WHICH CAD SB DISC AY 



399 



€—' 



the Corn plant. Borne by the wind, they settle upon 

 the plant and penetrate it wherever the tissues are 

 sufficiently tender, i. e., at the 

 terminal buds and at the base of 

 the leaves, inside the sheath. Any- 

 thing which tends to make the 

 Corn tender and succulent (e. g., 

 rich land and abundant water) 

 favors infection; moisture in the 

 air also helps to preserve the vital- 

 ity of the eonidia, which are in- 

 jured or killed outright by drying 

 up. The eonidia germinate by send- 

 ing out a germ-tube, which pene- 

 trates into the tissues of the Corn 

 plant, where the mycelium rapidly spreads to all parts. 

 (When food is not abundant they frequently unite in 

 pairs before sending out the germ-tube.) 



The best method of infecting the Corn is as follows : 

 Grow the spores in one of the above solutions (pref- 

 erably plum juice or Pasteur's solution with sugar), 

 until examination shows the formation of abundant 

 eonidia. "With a medicine -dropper place a few drops 

 of the liquid {a) on some Corn seedlings (with leaves 

 about half an inch long) grown between folds of moist 

 cloth or blotting-paper; leave them for at least twenty- 

 four hours more in the blotting-paper, then transplant 

 several of them to pots of sterilized soil (leaving the 



Spore of Corn-smut pro- 

 ducing eonidia (c). 



