52 



PLANT STRUCTURES 



habit is called parthenogenesis, which means reproduction 

 by an egg without fertilization. 



Fig. 33. A common water mould (Saprolegnia): A, a fly from which mycelial fila- 

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

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

 contact, the tube having penetrated to the egg; D and E, oogonia with several 

 eggs.— A-C after Thubet, D-F after DeBary. 



i 40. 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 ccenocytic mycelium branching extensively 

 through the substratum (Fig. 34). 



