MUSHROOMS. 25 



This class, however, does not include all the fleshy fungi, or 

 even all those in which there is a hymenium with spore-bearing 

 basidia. In a second class, much smaller, there is a similar 

 method of fruiting ; but the hymenium is not exposed, at least at 

 first. A common puff-ball is the best example. A microscopic 

 examination of the interior of a puff-ball shows that it is com- 

 posed of a mass of chambers the walls of which are covered with 

 basidia, the similarity of which to those in the class first treated is 

 very plain. The chambers, however, are partly filled with branch- 

 ing threads, together called the cajpilUthnn. When the puff-ball 

 is ripe and breaks open at the top, it is found that the chamber 

 walls have become disintegrated and that the disconnected 

 threads of the capillitiuni are left, together with an immense 

 collection of spores, all in a dry state and ready to be caught by 

 the first breath of wind. From the shape of the fruiting mass in 

 the puff-ball and allied forms this class is called the G-asteromy- 

 CETES. Since the class is small, our botanists have been able to 

 describe most of our species, at least those of the Eastern part 

 of the United States ; and fairly exhaustive systematic accounts 

 of them are to be found in the papers of Burt, Morgan, and others 

 on the Phalloids or Stink-horns, and of Peck, McBride, Morgan, 

 and others on the Puff-balls. 



Pructification by means of spore-bearing basidia unites these 

 two classes, together with others composed of less conspicuous 

 fungi, under a still more comprehensive name, that of Basidiomy- 



CETES. 



There still remain a few mushrooms not included in the groups 

 spoken of, namely, the Morels, HelveUas, and Pezlzas. The first 

 two are stalked, and roughly resemble the familiar Agarics ; the 

 last are shallow cups or fleshy expansions. A word as to the 

 form of their fructification must suffice. Examination under a 

 microscope of a bit of the outer or upper surface of one of 

 these plants will reveal structures at first sight much like those 

 in the Basidiomycetes. A mat of crowded slender cylindrical 

 cells is seen covering the surface ; none of these cells, however, 

 bear spores on their tips. Instead, some of them — not all — con- 

 tain spores in their interior. Each is, in fact, a little enclosure, 

 called an ascus, and if one that is mature be separated from the 

 rest, it will readily be seen to contain eight — almost invariably 

 eight — spores. At the proper time these escape from the asci. 



