Minnesota Plant Diseases. 23 



borne all over the surface of the plates, or gills, as they are 

 termed, and the spore area is thus very greatly increased in 

 size. Such fungi are known as gill fungi. Again, shelf fruit- 

 ing bodies are produced, which have holes all over the under 

 surface, as though pricked with a needle. The spores are 

 formed over the entire surface of these holes or pores. These 

 fungi are known as pore fungi. The fruiting bodies of other 

 fungi, again, may be more or less club shaped and branched or 

 unbranched. or they may be provided with numerous teeth as 

 in the bear's-head fungus. The puff balls are very common ob- 

 jects, especially towards the fall of the year; they are closed 

 fruiting bodies, with one or more enclosing membranes, which 

 open by a definite hole at the top, to allow of the escape of the 

 ripe spores. By pressing such a puff ball a dust of spores is 

 thrown out to the wind and scattered considerable distances. 

 Many relatives of the puff ball form fruiting bodies under- 

 ground, which look somewhat like truffles. The curious little 

 beaker-shaped structures containing egg-like objects are 

 fruiting bodies of the "birds-nest" fungi and the fruiting bodies 

 of the carrion fungi arc still more remarkably elaborated. 

 Here the spores are borne on the top of a very elastic stalk and 

 are found in a sticky mass which has an odor of carrion and 

 is much sought after by insects. The whole is enclosed in an 

 elastic covering which ruptures only when the spores are ripe 

 and then the stalk, previously held under pressure, is released 

 and lifts the spore area up very quickly into the air. In the 

 mildews, such as the common mildew on lilacs, in addition to 

 the loosely scattered summer spores, fruiting bodies are found 

 in the fall. They are usually very much smaller than a pin- 

 head. L'nder a microscope they are seen to be little, hard, 

 black-walled, capsule-like objects with curious appendages and 

 containing one or more sacs of spores. The black-knots on 

 cherry trees are fruiting bodies which contain, scattered over 

 the surface, numerous minute, pear-shaped depressions, which 

 are partially lined with sacs of spores. Very common in most 

 places, on wood or on the ground, are the cups of the cup- 

 fungi. These are fruiting bodies of various sixes with, in gen- 

 eral, a cup or beaker shape and are often brightly colored. 

 The inside of the cup is lined with sacs which burst open and 



