* 



38 Minnesota Plant Diseases. 



the animal. Many of the latter fungi have so become adapted 

 to this passage through the canal that they require the higher 

 temperature and the previous action of the digestive fluids of 

 certain animals before they will germinate. Such are some 

 of the little black "burnt-wood" fungi which always appear on 

 horse dung when the latter is allowed to remain for several 



weeks under a bell jar in moist 

 conditions. Besides these burnt 

 wood fungi, the common inhab- 

 itants of the dung of our ordi- 

 nary herb-eating animals are 

 members of the mushroom 

 group, the molds and the cup 

 fungi. The specialization of 

 many forms to the dung of cer- 

 tain species of animals is, of 

 course, explained in the prefer- 



FIG. 17. The same fungus as in Fig. r . . P . 



16, greatly enlarged. The spore case CllCC OI the .ailimal tor Certain 



has a svringe-bulb thread-end, below, r i , i r 1 i 



which "throws off the spore mass. foods, the remains Ol which 111 



its%ores n MfaSpLtograp^lb" v. the animal dung are most favora- 

 K - Butters - b!e for the fungus. 



Earth-dwelling habit. On the forest floor or on the ground, 

 in fields, from the thaw of early spring until snow flies in fall, 

 one sees fungi of one sort or another. Such fungi appear to 

 take their substance from the soil since their mycelium is 

 branched and scattered in the earth. However, if these fungi 

 were removed and placed in pure sand where no plant or ani- 

 mal remains were present, or where no substances had been 

 leached out of dead wood, leaves or roots, and diffused through 

 the soil, they would he utterly unable to develop. That is to 

 say, they are unable to live in plant-free or animal-free soil, and 

 so-called earth-inhabiting fungi in reality draw their nourish- 

 ment from substances deposited in the soil or in solutions in 

 the soil water. It is very noticeable that one finds numerous 

 fungi in the neighborhood of old, partially decayed stumps or 

 tree trunks, where bits of the wood have been scattered about 

 and where the water has long been soaking through the wood. 

 The forest floor is of course usually a humus soil, one which 

 has been built up for inches, or even feet, by the deposit of 



