Minnesota Plant Diseases. 



FIG. 13. A birds-nest fungus. To the 

 left are unopened fruiting bodies; 

 to the right a section of the same; 

 the eggs are chambers, carrying 

 spores, and the chamber stalks be- 

 come sticky when moist and prob- 

 ably catch in the legs of insects and 

 are thus distributed. After Engler 

 and Prantl, and Sachs. 



rity very qiuckly elevated by a Sponge-like stalk to a conspicu- 

 ous height. The spore-mass contains substances that emit a 

 very strong odor as of carrion; hence the common name of 

 these plants. This odor is very attractive to many insects and 

 apparently the spore mass contains abundant food material 

 for it very soon disappears as a result of the numerous visits 

 of flies and other insects. In some forms of these carrion 

 fungi pure white veil-like or lace-like mantles in appearance 



much like a large-meshed Wels- 

 bach mantle are produced. 

 Certain tropical forms, more- 

 over, add a phosphorescence to 

 these mantles so that they at- 

 tract nocturnal insects, and such 

 forms open usually at or just be- 

 fore dusk. Certain molds inha,b- 

 it the bodies of larvae of insects, 

 living parasitically on them. An 

 insect thus infected may carry 

 the fungus to a considerable distance and after death numerous 

 spores will be formed which may infect new larvae. The si^k- 

 worm is often preyed upon by these fungi. 



Distribution by other animals. Vertebrate animals are also 

 occasionally agents of spore distribution. Squirrels often feed 

 on certain mushrooms thereby carrying the spores off into 

 their holes. These fungi are the so-called wound parasites 

 which start life as saprophytes in the dead heart-wood of trees 

 and finally grow out into the sap-wood and kill the tree. In 

 the well-protected shelter of such squirrel holes a wound para- 

 site can get a good start. Rabbits and other burrowing ani- 

 mals often brush up against the fungus fruiting bodies of root- 

 inhabiting forms and carry the spores in their furry coats. 

 Truffles are probably distributed by those animals which feed 

 on them. There is a very large class of fungi which inhabit 

 the dung of certain animals. Such fungi often grow from 

 spores which have passed through the alimentary canals of 

 these animals. The near relatives of the shaggy-mane mush- 

 room are good examples of these fungi. The common com- 

 mercial mushroom also regularly inhabits dung and is there- 



