62 



SIPHONED. 



out distinct differentiation in stem- or leaf-structures, sometimes 

 (e.g. Halimeda) it is very much incrusted with lime. In the 

 early stages it is unicellular (later, often multicellular), very 

 much branched, with the branches, at any rate partly, so united 

 or grown in amongst one another (Fig. 60) that an apparently 

 parenchymatous cellular body is formed. Akinetes oraplanosporos 

 are wanting; zoospores (or 

 gametes ?) may be developed in 

 some species, however, in special 

 swollen sporangia. Fertilisation 

 similar to that in Bryopsis occurs 

 perhaps in G odium. They are 

 all salt water forms. 



Order 8. Valoniaceae. The thal- 

 lus is generally multicellular, without 

 differentation into stem- or leaf-struc- 

 tures, but the cells are sometimes 

 united together and form a leaf-like 

 reticulate expansion (e.g. Anadyomene). 

 Zoospores are known in some, and 

 they are then formed directly in the 

 vegetative cells. In others (e.g. 

 Valdliia), a mass of protoplasm, which 

 7i) ay be separated through the damag- 

 ing of a cell, can surround itself with 



Fia. 59. Caulerpa prolifera (natural size). 



a cell-wall, and grow into a new plant. No other modes of reproduction are 

 known. The most important genera are : Valonia, Siphonocladus, Chamcedoris, 

 Struvea, Mtcrodictyon, Anadyomene. They are all salt water forms. 



As already pointed out, the Valoniacece occupy a somewhat central position 

 among the Siphoneae, and present points of similarity and contrast with the 

 Botrydiacece and the Bryopsidacece through Valonia, with the Dasycladacece 

 through Chamcedoris, and also with the Cladophoraceee through Siphonocladus, 

 and Struvea. 



