SECT. I 



CRYPTOGAMS 



381 



living fishes. Asexual propagation is effected by club-shaped sporangia (Fig. 306) 

 whicli produce numerous bieiliate swarni-spores. The sexual organs develoi) on 

 older branches of the mycelium (Fig. 307, a). The oogonia give rise to a larger (as 

 many as 50) or smaller number of egg-cells, rarely only to a single one. At first 

 the oogonium contain.^ numerous nuclei, most of which, however, degenerate; the 

 remaining nuclei divide once niitotically into daughter nuclei, of which some again 

 degenerate, while round the re- 

 maining nuclei the oospheres be- 

 come delimited. The egg-cells are 

 always uninucleate. The tubular 



an theridia, with a number of nuclei 0__ 



that undergo one mitotic division, 

 a])p]y themselves to the oogonia 

 and send fertilising tubes to the 

 egg-cells. One male nucleus enters 



the egg-cell and fuses with its 

 nucleus (Fig. 308). The oospore 



Fio. ■ 300. — Sajrrolegnia 

 bieiliate zoospores, s-. 

 from the sporangium. 



'inixla. The 

 are escaping 



Fir:. 307. — Saprolegnia m ixta. Hypliafi bearing the 

 sexual organs; a, antheridium which has sent 

 a fertilisation tube into the oogonium ; oi, 

 egg-cell ; (fi, oospore eiiclosoil in a cell wall ; op, 

 partliogenetio oospores ; ij, young oogoniiini. 

 (After G. Klebs.) 



after fertilisation acquires a thick Avail. In some forms belonging to this family and 

 to the Peronosporeae the formation of antheridia is occasionally or constantly sup- 

 pressed ; the oospores develop parthenogenetically without being fertilised (Fig. 307). 

 3. The Chytridiaceae (*°) are microscopically small Fungi parasitic on aquatic 

 or land plants and in some cases on animals. The non-septate mycelium is feebly 

 developed, and is frequently reduced to a single sac-shaped cell inhabiting a cell 

 of the host. Asexual multiplication is effected by means of swarm-spores provided 

 with one or two cilia. In the simplest forms the entire cell becomes converted 



