268 



PLANT STUDIES 



habit is called parthenogenesis^ which means reproduction 

 by an Qgg without fertilization. 



Fig. 233. A common water mould (Saprolegnia): A, a fly from which mycelial fila- 

 ments of the parasite are growing; B, tip of a branch organized as a sporangium; 

 C, sporangium discharging biciliate zoospores; F, oogonium with antheridium in 

 contact, the tube having penetrated to the egg; Z> and B, oogonia with several 

 eggs.— J.- C after Thuret, Z>-i^ after DeBary. 



181. Mucor. — One of the most common of the Mucors, or 

 "black moulds," forms white furry growths on damp bread, 

 preserved fruits, manure heaps, etc. It is therefore a 

 saprophyte, the coenocytic mycelium branching extensively 

 through the substratum (Fig. 234). 



