246 



ALG^ 



Their arrangement, on which the deHmitation of the orders is largely 

 made to rest, varies greatly. They may be collected into wart-like sori 

 on the surface of the thallus, appearing sometimes like dark dots uni- 

 formly distributed, or they may spring from the branches. In Sporochnus 

 (Ag.) the unilocular sporanges are collected into a peculiar receptacle 



J; tA 



Fig. 219. — Sp07-ochn7is fieduncidatus Ag. a, natural size ; b, c, receptacle containing 

 zoosporanges ; d, unilocular zoosporange ( x ico). (After Kiitzing.) 



consisting of pear-shaped swellings near the extremity of the branches, 

 composed of a dense mass of filaments on which the sporanges appear 

 as lateral branches. Very little is known of the further history of the 

 zoospores. In Scytosiphon lomentarium (Ag.) Berthold ('Mittheilungem 

 Zool. Stat. Neapel,' ii., 1881) has observed conjugation of the swarm- 



