260 



BIOLOGY OF THE PROTOZOA 



Conjugation and fertilization are entirely unknown in the Order 

 and reproduction is mainly by longitudinal division which may 

 lead to catenoid {Chlorodesmns, Cyclonr.vis), arboroid {Dinobri/on, 

 Hyalobryon, Fig. 126) or spheroidal {Synura, Uroglena, Uroglen- 

 opsis, Chry!:<()S})h(FrcUa, Syncrypta) colonies. Many of the Chryso- 

 monadida round out, lose their flagella and pass into a quiescent 







^ '-^-/f 



■A 1.1 





A B 



Fig. 127.- — Hydrurus fcetidus. B, character of growth; A, end of single branch 

 with monads in the gelatinous matrix; C, motile stage of monad; D, E, side and top 

 view of cyst. (^A, C, D, E, from Doflein after Klebs; B, from Pascher.) 



phase. In most such cases reproduction ensues and a Palmella- 

 stage results which is purely facultative in many types, but in some 

 groups, notably in the sub-order Chrysocapsina, the Palmella-stage 

 is dominant, the most extreme case, Hydrurvs, with its apical 

 growth and method of branching, being highly suggestive of the 

 multicellular algse (Fig. 127). 



