226 



BIOLOGY OF THE PROTOZOA 



A. Exogenous Budding.— In Acanthocystis aculeata according to 

 Schaudinn (1896) and in Wagnerella borealis according to Zuelzer 

 (1909) the nucleus of the cell divides one or more times by simple 

 constriction and without the formality of mitosis or participation 

 of central granule. The minute nuclei thus formed wander to the 

 periphery of the cell where they are pinched off in minute cells. 

 In Acanthocystis these buds form minute amebae which after four 



Fig. 115. 



-Ephelota biitschliana, a suctorian. Budding individual with five exogen- 

 ous buds. N, branching macronucleus. (After Calkins.) 



or five days of activity settle down and metamorphose into young 

 Heliozoa (Schaudinn). The buds have no central granule, but during 

 metamorphosis a kinetic element emerges from the nucleus and 

 this becomes the central granule of the adult Acanthocystis (Fig. 50, 

 p. 95). In Wagnerella borealis, according to Zuelzer, the buds which 

 are formed in a similar manner are flagellated, but her description in 

 other respects follows that of Schaudinn. 



In Infusoria, particularly in Suctoria, exogenous budding is not 



