EUTHALLEPHYTA— EUMYCETES— OOMYCETES 209 



oogonia or antheridia. The oogonia may give rise to one or many oospheres or 

 egg cells. The antheridia are tubular and spring from the hyphae below the 

 oogonia. They apply themselves to the oogonia and send out fertihzation 

 tubes to the egg cells. The latter then develop into oospores. The asexual 

 method occurs as follows : An examination of the young threads of Saprolegnia 

 will show long filaments which in places are filled with granular protoplasm. 

 Some of these threads are separated from the rest of thread by a cell-wall. 

 Soon the protoplasm arranges itself into polygonal areas. When mature the 

 sporangium breaks and the zoospores are discharged into the water. When 

 emptied a new sporangium is formed by the filament growing up into the old 

 one, or in some cases a branch buds out below the oogonium. 



Recent investigations indicate that the egg cell contains numerous nuclei, 

 but as a general thing they are all degenerate but one. The antheridia also 

 contain many nuclei. According to the investigations of some, one male nucleus 

 enters the egg cell and fuses with its nucleus. 



Trow,* Davis,t and Kauffman X have thrown light upon the development of 

 the reproductive body. 



Saprolegnia. Nees von Esenbeck. Water mould 



Delicate branching hyphae, zoosporangia open from a terminal pore, zoo- 

 spores pear-shaped with 2 terminal cilia. About 11 species common on decaying 

 objects in water. 



Saprolegnia inonoica (Pringsheim) De Bary 



Zoosporangia cylindrical ; antheridia usually in close proximity to the 

 oogonia frequently originating from the same branch ; oogonia from short 

 lateral branches ; oospore spherical 16 to 22 m in diameter, germ tube formed 

 in germination. 



Distribution. Widely distributed in North America and Europe. 



Pathogenic properties. Occurs on dead insects thrown into the water, par- 

 asitic on living fish and crayfish. Frequently troublesome in aquaria. The S. 

 Thureti, DeBary and Achlya prolifera are found on sick fish and crayfish. Hoff- 

 mann in 1867 stated that fish in aquaria died under the influence of Miicor 

 niuccdo and Saprolegnia. 



It is doubtful, however whether the Mucor produced death. 



EASIDIOMYCETES 



Conidiophores arise from a many-celled, well developed mycelium, hyphae 

 either separate or forming masses; texture soft, powdery or leathery: the 

 spores various, in the most common type, the basidiospore is borne on special 

 structures known as basidia, from which arise little bodies called sterigmata into 

 which some of the protoplasm of the basidium passes. In one group the mycel- 

 ium consists of septate, branched threads, at maturity nearly disappearing be- 

 cause of gelatinization ; mycelium gives rise to chlamydospores formed en- 

 dogenously; reproduction sexual and asexual, usually the latter; comprises 

 the sub-classes, Hemibasidii and the Eubasidii. 



• Annals of Botany. 18:541. 

 t Bot. Gaz. 35:233. 

 JAnn. of Bot. 22:361. 



