Phylum Phaeophyta [57 



amoeboid. By Pascher's own principle of the repeated evolution of body types, 

 these groups are surely artificial. Here most of them are broken up and their mem- 

 bers distributed between the two chrysomonad orders according to whether the 

 flagella of their motile stages are paired or single. It is not possible to divide by this 

 character ameboid forms not known to produce flagellate stages; these are lumped 

 in the second order. 



fc) Since flagella appear to have evolved as a device for the dissemination of 

 unicellular pigmented organisms, examples whose vegetative state is that of clusters 

 of non-motile cells are placed in each order before those which are flagellate in 

 the vegetative condition. 



The two chrysomonad orders are particularly characterized by production of 

 leucosin. They are further characterized by production of resting cells of a type 

 called statospores. This occurs by the deposition within the protoplast of a globular 

 shell impregnated with silica, punctured by a single pore, and often marked on the 

 outer surface by warts, spines, or ridges, of definite pattern. The external protoplasm 

 migrates through the pore to the interior of the shell, and the pore is then closed 

 by deposition of a silicified plug. 



The group which is treated as the third order of the present class includes the 

 typical Heterokonta. Compared with typical green algae, these organisms give the 

 impression of a markedly distinct class; placed next to the chrysomonads, they 

 appear scarcely entitled to this rank. Their name is the oldest applicable to the 

 present class, and is accordingly so applied. If it appear expedient to maintain the 

 typical Heterokonta as a distinct class, the remainder of the present one will be 

 called Chrysomonadinea [Chrysomonadineae] (Engler) Pascher. 



Of including the choanoflagellates and anisochytrids in the present class as addi- 

 tional orders, one may say that it is not contrary to current knowledge. 

 1. Mostly pigmented; non-pigmented examples 

 mostly producing motile cells with two 

 fiagella. 



2. Brown or colorless. 



3. Producing motile cells with two 



flagella (exceptionally more) Order 1. Ochromonadalea. 



3. Producing motile cells with one 

 flagellum; or without known flagel- 

 late stages Order 2. Silicoflagellata. 



2. Green Order 3. Vaucheriacea. 



1. Non-pigmented, producing motile cells with 

 one flagellum. 



2. Predatory, flagellate in the vegetative 

 condition, each cell bearing a collar-like 



protoplasmic ridge Order 4. Choanoflagellata. 



2. Parasitic or saprophytic, the vegetative 



cells non-motile, walled Order 5. Hyphochytrialea. 



Order 1. Ochromonadalea [Ochromonadales] Pascher Siisswasserfl. Deutschland 



2: 10,51 (1913). 

 Suborder Monadina Biitschli in Bronn KI. u. Ord. Thierreichs 1 : 810 (1884). 

 Order Isochrysidales Pascher op. cit. 10, 42. 

 Order Syracosphaerinae Schiller in Arch. Prot. 51: 108 (1925). 



