1 86 Minnesota Plant Diseases. 



over the hole from which it was torn loose. The puff-ball fruit- 

 ing body in the very young stages is internally fleshy, more or 

 less solid, and usually pure white, and in this condition is edi- 

 ble and frequently sought by mushroom eaters. Caution must 

 be exercised to prevent mistaking for them the young button- 

 like stages of the poisonous gill fungi, which are not at all un- 

 like certain puff-balls. Puff-ball fruiting bodies vary enormous- 

 ly in size. The smallest are little larger than good-sized peas 

 while the giant puff-ball, a form much sought for by mycopha- 

 gists, has been frequently collected in Minnesota a foot or more 

 in diameter. In the youngest stages the interior of the puff- 

 ball is chambered and the chambers are lined with a palisade 

 of basidia. The mycelium of certain puff-balls has been de- 

 scribed as furnishing the mycorrhizal threads which live in part- 

 nership with roots of certain trees. These fungi are otherwise 

 saprophytic in habit. (Figs. 10, 81, 90, 91, 93.) 



Birds' -nest fungi (Nidulariinece). This group of basidium- 

 bearing fungi would at first sight be scarcely recognized as a 

 close relative of the puff-balls. Such it is, however, with pecul- 

 iar variations from the typical puff-ball structure. The cham- 

 bering here becomes permanent and the chambers are lined as 

 usual on the inside with a palisade ; they become separated by 

 the breaking down of the threads between. The chambers thus 

 come to look like small hard-coated egg-like bodies, which lie 

 loosely within the walls of the puff-ball. These walls open at 

 the apex by a broad-mouthed opening, which in the earliest 

 stages is closed by a parchment-like membrane, so that at ma- 

 turity the fruiting body has an open beaker-like form. In the 

 beaker or cup lie the egg-like chambers. The latter are in our 

 commoner forms attached to the wall by thin stalks of exceed- 

 ingly elastic fungus threads which are so extensible that in wa- 

 ter they can be drawn out to a length of six inches or more 

 from one-fourth inch or less in the dry state. This stalk may 

 serve to attach the fungus to the legs of insects and again from 

 here to the twigs or trunks of trees. The stalk is somewhat gel- 

 atinous which aids in the fastening of the stalk. The spores are 

 thus distributed in packets, which are the separated chambers, 

 and they germinate directly from the interior of the chambers. 

 The birds'-nest fungi are saprophytes with chiefly wood- or 



