SECTION 17.] 



THALLOPHYTES. 



173 



cells lengthen and branch, growing by the absorption through their whole 

 surface of the decaying, or organizable, or living matter which they feed 

 upon. In a Mushroom (Agaricus), a knobby mass is at length formed, 

 which develops into a stout stalk {Stipe), bearing the cap {Pileus) : the 

 under side of the cap is covered by the Hi/menium, in this genus consisting 

 of radiating plates, the gills or Lamellee ; and these bear the powdery spores 

 in immense numbers. Under the microscope, the gills are found to be 

 studded with projecting cells, each of which, at the top, produces four 

 stalked spores. These form the powder which collects on a sheet of paper 

 upon which a mature Mushroom is allowed to rest for a day or two. (Fig. 

 581-586.) 



517. The esculent Morel, also Sphaeria (Pig. 585, 586), and many other 

 Fungi bear their spores in sacs (asci) exactly in the manner of Lichens 

 (515). 



518. Of the Moulds, one of the commoner is the Bread-Mould (Fig. 

 587). In fruiting it sends up a slender stalk, which bears a globular sac ; 



Pio 581 Agaricus campestris, the common edible Mushroom. 582. Section 

 of cap and stalk. 583. Minute portion of a section of a gill, showing some spore- 

 bearing cells, mnch magnified. 584. One of these, with its four spores, more 



"fig. 585. Sphairiarosella. 586. Two of the asci and contained double spores, 

 quite like those of a Liehen; much magnified. 



