140 The Mastigophora 



Ceratium (106) may capture and presumably digest microorganisms 

 outside the theca by means of pseudopodial nets (Fig. 4. 18, A, B). These 

 pseudopodia apparently arise from cytoplasmic papillae extending 

 through pores in the theca (Fig. 4. 17, F). 



The life-cycle may be apparently simple, or may show dimorphism or 

 polymorphism (159). Sexual phenomena have been reported in several 

 species (Chapter II). Fission is typically oblique (Fig. 2. 2, A-H) and, 

 in armored species, involves regeneration of different portions of the 

 theca by the daughter organisms. In contrast, as represented by certain 

 species of Glenodinium, fission may occur within the theca and the 



'-nv%'^ 



Fig 4. 18. A, B. Capture of microorganisms by pseudopodial networks 

 in Ceratium 'hirundinella; x425 (after Hofender). C. Oxyrrhis marina, four 

 food vacuoles, nucleus in outline; x885 (after Hall). 



daughter organisms are liberated as naked forms which later secrete a 

 theca. In other cases, each daughter organism develops a new theca 

 before it emerges from the parental one. Incomplete separation after 

 fission may result in chains (Fig. 4. 19, I), which are characteristic of 

 certain species but not of others. Reproductive cysts, known in a number 

 of species, may be more or less spherical ("pyrocystis" type) or some- 

 times crescentic ("crescent-cysts"). In Gymnodinium lunula (159), cres- 

 cent-cysts are developed within a pyrocystis-stage. Fresh-water species 

 may produce a thick-walled protective cyst, as in Ceratium hirundinella 

 (Fig. 2. 15, A). A palmella stage in which fission occurs is known in 

 some species, and is the dominant phase in Gleodinium (Fig. 4. 24, C, 

 D). In Amyloodinium ocellatum (Fig. 4. 19, A-C) the dominant phase 



