68 Reproduction and Life-Cycles 



Fig. 2. 10. A, B. Paradesmose in Tritrichomonas augusta; x2390 (after 

 Kofoid and Swezy). C-E. Paradesmose in Metadevescovina cuspidata; early 

 division (C), x2160; nuclens divided and other organelles duplicated (D), 

 xl800; later stage with very long paradesmose (E), xl440 (after Kirby). F, G. 

 Fibrillar paradesmose in Giga)itonw>ias herciilea; late anaphase (F), xl710: 

 nuclear division completed (G), x725 (after Kirby). H. Centromeres in Holo- 

 mastigotoides; portions of chromosomes indicated diagrammatically; xl260 

 (after Cleveland). I, J. Extranuclear spindle in Pseudotrichony?npha; chromo- 

 somes moving toward poles (I), x935; later stage (J), chromosomes not shown, 

 x735 (after Cleveland). Key: a, axostyle; c, cresta; ce, centromere; p, parades- 

 mose. 



The significance of the persisting endosome in Euglenida and certain 

 dinoflagellates (Fig. 2. 11, A-D) is uncertain. Although this structure oc- 

 cupies an axial position and is divided in mitosis, there is no good evi- 

 dence that the endosome is analogous to an intranuclear spindle. 



The macronucleus 



The simpler macronuclei often divide by mere elongation and 

 constriction into approximately equal parts, although unequal division 

 occurs occasionally (71). Division of the compact macronucleus is not 



