THE FUNGI 83 



numerous nuclei. In the common water-moulds the 

 reproductive cells are also similar to those of the Si- 

 phonese. There are sporangia (Fig. 21, B) formed by 

 the cutting off of the end of a filament, and the proto- 

 plasm of this sporangium then divides into a large 

 number of biciliate zoospores (C), which, on escaping, 

 germinate promptly and form new plants. 



The sexual organs of the water-moulds also recall 

 those of Vaucheria, but the oogonium usually contains 

 more than a single egg-cell, and fertilization is not 

 effected by motile spermatozoids, but directly by a tube 

 which is sent out from the antheridium and penetrates 

 the wall of the oosronium. Through this tube the con- 



o o 



tents of the antheridium is transferred to the egg-cell, 

 Avhere by a fusion of the nuclei of the two cells, fertili- 

 zation is effected. The fertilized egg thereupon secretes 

 a thick wall and becomes transformed into a spore, as 

 in the green algse. 



In some species of Saprolegnia the spores develop 

 without fecundation, antheridia being entirely absent. 

 There are some interesting intermediate conditions 

 where the antheridium is present, but is entirely func- 

 tionless. This degeneration of the reproductive organs 

 is probably correlated with the parasitic or saprophytic 

 habits of the plants, and is a phenomenon of frequent 

 occurrence among the higher fungi, as we shall see, 

 where the great majority show no trace of any sexual 

 reproduction. 



Still more like the algae are the species of the rare 

 genus Monoblepharis, where fertilization is effected by 

 ciliated spermatozoids. Another remarkable genus, 

 Myrioblepharis, recently discovered by the American 



