no MYCOLOGY 



habit and formation of motile spermatozoids, Brefeld considers Mono- 

 blepharis to be the most primitive of the Oomycetales. 



Family 2. Saprolegniace^. — The members of this family, as 

 their name indicates, are saprophytes on both dead plants and animals 

 in water with the exception of the fungus which causes the salmon 

 disease and it is both a saprophyte and a facultative parasite. The 

 hyphae in the vegetative condition are relatively large, arising from 

 delicate rhizoids which penetrate the substratum. Swarm spores 

 which are biciliate are formed in terminal, long, tubular zoosporangia 

 opening by an apical pore through which the zoospores crowd their 

 way out into the water. Sometimes, as they escape, they collect into 

 ball-shaped masses which are caused to slowly roll about by the activity 

 of the cilia. The female sexual organs, the oogonia, are terminal on 

 the branches of the thallus hyphae. Several oospheres without dis- 

 tinction of periplasm are formed inside of a single oogonium, and 

 sometimes, as many as thirty or forty are found. The antheridia, 

 which are club-shaped, are formed on slender branches of the mycelium 

 which also bear the oogonia, or which are distinct from those 

 which are oogonial bearers. These antheridia approach the oogonia 

 and an antheridial beak is formed which penetrates the wall of the 

 oogonium and comes into contact with the oospheres by growing from 

 one oosphere to another. Sometimes the antheridia, as in Saprolegnia 

 monilifera, are not produced at all and the oogonia develop partheno- 

 genetic oospores which germinate after a rest period of a few days to 

 several months. The series representing reduction in sexuality begins 

 with such forms as Saprolegnia monoica with an oogonium and an 

 antheridium which develops a fertihzing process through Achlya 

 polyandra, which forms antheridial branches which do not touch 

 the oogonia, to Saprolegnia monilifera without any trace of antheridia. 

 Androgynous forms are those in which the same hyphal branch 

 develops both antheridia and oogonia and the diclinous species 

 like Saprolegnia dioica and Achlya oblongata ar.e those in which the 

 antheridia and oogonia are borne on distinct branches. 



Saprolegnia ferax usually attacks only fishes, tadpoles and the 

 spawn of frogs. It appears on aquarium-kept fishes on the sides of 

 the body at the tail end, or among the gills. In the latter place, if 

 abundant, it frequently causes asphyxiation and before this state is 

 final the fish turns over on its back and rises to the surface. In the 



