Hhodophycece 35 



of the oosphere of the green Alga*. The male organ is an an- 

 theridium of variable form which gives origin to large numbers of 

 male cells. Each male cell opens at the apex and sets free a 

 rounded, nucleated mass of protoplasm, without a cell-wall and 

 without cilia, known as a spermatium (or pollinoid). Fertilization 

 takes place by the attachment of the spermatium to the apex of 

 the trichogyne and the union of their contents. As the nucleus 

 of the spermatium disappears, it travels down the trichogyne and 

 unites with that of the carpogonium, this fusion having been 

 observed by Osterhaut in Batrachoxpermum Boryanum 1 . 



The result of the fertilization of the carpogonium is the 

 development of a fructification known as a cystocarp (or sporocarp), 

 and the different groups of the Rhoclophycese are characterized by 

 the method of formation of this fructification. Sometimes the 

 cystocarp is developed directly from the carpogonium ; but, fre- 

 quently, the fertilizing influence is handed on to other cells in 

 the neighbourhood of the carpogonium, and conjugation occurs 

 between outgrowths of the fertilized carpogonium (known as 

 ooblastem a filaments) and certain auxiliary cells, the final result in 

 all cases being the development of the cystocarp and the production 

 of carpospores. Whatever be the method of formation of the 

 cystocarp, the carpospores are always developed on a tuft of 

 filaments which spring from fertilized cells and which are known 

 as goniinoblasts. 



The class is subdivided into four orders : 



Order I. Nemalionacece. This order includes four families, 

 of which the Lemaneacese is exclusively fresh- 

 water, and the Helminthocladiea? includes several 

 freshwater genera. 



Order II. Cryptonemiacew. One family of this order, the 

 Squamariacese, contains a genus of which there 

 are several freshwater species. 

 Order III. Gigartinacece. Exclusively marine. 

 Order IV. Rhodymeniacece. Exclusively marine. 

 In addition to the four orders just enumerated, another group 

 of Algae known as the Bangiacew is often included in the Rhodo- 

 phycece, but the systematic position of this group is very uncertain. 



1 Osterhaut in Flora, Ixxxvii, 1900. 



32 



