214 RHODOPHYCEAE 



(b) The development of special nutritive cells which will 

 ultimately replace the auxiliary cells in fulfilling the nutritional 

 requirements. 



(c) The development of the carposporic filaments, or gonimo- 

 hlasts, into creeping threads w^hich may be able to utilize food 

 contained in neighbouring cells. 



(2) Cryptonemiales. 



Here there are definite pit connexions to the auxiliary cells, 

 which serve not only for nutrition but also as starting points for 

 the gonimoblast filaments. The auxiliary cells develop on special 

 branches before fertilization and are actively concerned in the post- 

 fertilization processes. 



(3) Gigartinales. 



A normal intercalary cell of the mother plant is set aside as an 

 auxiliary cell before fertilization. 



(4) Rhodymeniales . 



The auxiliary cells are small, and though cut off before fertiliza- 

 tion they only develop after that process has taken place. 



(5) Ceramiales. 



The auxiliary cell is cut oflP from a support cell after fertilization 

 and as a direct consequence of the process. Series (3)-(5) should 

 probably be regarded as examples of progressive reduction. 



Auxiliary cells absent (Nemalionales) 



(Gehdiales) No 



Auxiliary cells present before (Cryptonemiales) procarp 

 fertilization (Gigartinales) 



(Rhodymeniales) 

 Auxiliary cells develop after (Ceramiales) !- Procarp 



fertilization J present 



In 1926 Sjostedt created tw^o new orders, the Sphaerococcales and 

 the Nemastomales, but in this volume the genera composing these 

 two new orders are retained in the orders to which they have 

 belonged in the past. 



The antheridial plants, which are often paler in colour and more 

 gelatinous, were first mentioned in a letter to Linnaeus in 1767 



