198 REPRODUCTION OF A WATER MOULD 



to several gametes being formed in an oogonium (Fig. 130, D). 

 The antheridia, however, develop several non-motile male gam- 

 etes. This peculiarity of the gametes is perhaps due to their 

 exposure to atmospheric conditions, as would be the case when 

 growing upon floating organic matter. The lack of water for 

 the transport of the male gametes is nicely met by a tubular out- 



FIG. 130. Features in the life history of the water moulds: A, fly in- 

 fected with Saprolegnia, showing the tubular threads of the fungus radi- 

 ating out from its body. B, tip of a tube magnified, showing an early 

 stage in the formation of the sporangium. C, sporangium discharging 

 zoospores. D, Reproductive organs of a related fungus, Achlya o, 

 oogonium containing four female gametes; an, antheridium with tubes 

 penetrating oogonium for transport of male gametes. 



growth of the antheridium which penetrates the oogonium when 

 it ruptures, discharging the males in the immediate vicinity of 

 the female gametes (Fig. 130, D, an). In the majority of the 

 species, singularly enough, the female gametes germinate with- 

 out being fertilized. The gametospore germinates as in Van- 



It should be stated that, in related forms, large multiciliate 

 zoospores, like those of Vaucheria, are formed and also motile 

 male gametes. It is also important to note that there are several 



