APPENDIX 



487 



The mycelium may propa- 

 gate only vegetatively, often 

 forming dense masses (scle- 

 rotia) (Fig. 208), to tide over 

 unfavorable times, or they 

 may produce reproductive 

 cells (spores) having the func- 

 tion of seeds. The forms of 

 spores and the ways in which 

 they are borne are manifold 

 and serve as the chief means 

 of distinguishing one fungus 

 from another. Some are 

 borne in sacs (asci, Fig. 209); 

 others on basidia (Fig. 210). 

 The asci may be in perithecia (Fig. 209), or uncovered. Basidia 

 are often borne upon the surface of the gills of toadstool-like 

 fungi (Fig. 184), or upon the Uning of the pores of similar struc- 



FiG. 208. — Sclerotia of lettuce sclerotini- 

 ose, natural aize. Original, 



ascospore 



■ascusmW- ^ 



emcospores w ■ , 

 ^-^ ' Uigermmofwrr 



Fig. 209. — Perithecium with aaci. 



