222 BIOLOGY OF THE PROTOZOA 



continues and at the same time minute buds of protoplasm appear 

 at the bases of these disappearing membranelles. These buds grow 

 pari passu with the dwindling motile organs until finally the latter 

 are entirely absorbed and the buds have developed into functional 

 membranelles. In the same way each cirrus is replaced by a new 

 growing bud quite regardless of the position in anterior or posterior 

 half. Undulating membranes are similarly withdrawn and replaced 

 by new ones so that the young cells formed by division of the meta- 

 morphosing parent cell receive a full set of new motile organs com- 

 mensurate with the size of the young organisms. The phenomenon 



Fig. 112. — Chilodon uncinatus. New mouth and basket replacing the old ones 

 prior to cell division. (N.B.) New mouth and basket; (O.B.) old mouth and basket 

 before degeneration and disappearance; (P.B.) new mouth and basket for the pos- 

 terior individual after division. (After MacDougall.) 



is very striking in forms with giant cirri such as the jumping types 

 of Euplotidae— Diophrys or Uronychia. In the latter genus the 

 great posterior cirri are the most conspicuous organs of the cell 

 (Fig. 111). The buds which are to grow and replace them are appar- 

 ent before there is other external evidence of the approaching 

 division and even before the nucleus has concentrated into its divi- 

 sion form. At the same time similar buds appear in the division 

 zone, that which is destined to form the giant-hooked cirrus appears 

 first and is always larger than the others which appear one after the 

 other according to ultimate size. Owing to their minute size it 

 has not been determined whether or not the individual cilium is 



