274 



BIOLOGY OF THE PROTOZOA 



nium lumila (Fig. 130) according to Schiitt is found in the plankton 

 as a large cyst-like organism, not unlike Noctihica, containing a 

 single nucleus. This divides four times and 16 daughter cells are 

 formed each of which develops into a "horned cyst" and gives rise 

 to 8 small Gymnodinium-like products (Fig. 130, 1, 2, 3, 4, 5). 

 Schiitt's inference that these ultimate products are gametes which 

 conjugate and give rise to the spherical cysts, has not been con- 

 firmed. Conjugation stages in Ceratium hinmdineUa have been 

 described by G. Entz (1910), and by Zederbaur (1904), which recall 

 the sexual processes of the desmids, the zygote according to their 



Fig. 133. — Haplozoon clymeneUa, regarded by Chatton as a parasitic dinoflagellate; 

 (a) primary attaching individual which gives rise to a chain of cells terminating in 

 cells with four nuclei {h) . (After Calkins.) 



interpretation giving rise to the characteristic "four-horned cyst." 

 The great variability, and the frequency of pathological conditions 

 in Ceratmm make this so-called conjugation process questionable. 

 The Blastodinidte are all jjarasitic and have lost most of the 

 characteristic dinoflagellate structures, the affinities being indi- 

 cated, as in Noctihica, by the structure of the spores (dinospores). 

 Some are external parasites on appendages and gill filaments of 

 pelagic animals; on animals, on diatoms (Pmdsenella) , or on eggs 

 of copepods, etc. Others are internal parasites of digestive tract 

 or coelom {Syndiniwn). Some types {Ayodinmm, Farapodiniinu, 



