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Annals of the South African Museum. 



of which the posterior part forms the crown (fig. 3, I ; Plate XLI, 

 C-D). 



(9) " Flask " Stage. As more and more of the colony emerges 

 the structure assumes the shape of an inverted flask with dented 

 base and turned back flange (the lip of the phialopore) round the nar- 

 rowing neck (fig. 3, J ; Plate XLI, E, F). The changes in shape of the 

 cells and cilia formation have gradually spread into the anterior half, 

 at this stage the flange alone remaining in the stretched condition. 

 This flange or fringe is sometimes distinctly three-, more rarely four- 

 lobed, more often it is very irregular in appearance. 



(1) 1.4 p.m. 



(2) 1.8 p.m. 



(3) 1.12 p.m. 



FIG. 4. Inversion of daughter colonies. Cell detail. 



A, Cells and protoplasmic connections from anterior half about stage G ; B, cells 

 from posterior pole, stage F, G ; C, cells from recently inverted colony ; D, 

 closing phialopore of colony shown in fig. 3. 



A-C x about 2500; D x about 1250. 



(10) The cells of the fringe contract, become more closely packed, 

 the lobes fold inward to fill up the contracting pore. The dent at 

 the opposite anterior pole of the inverted colony gradually straightens 

 out (fig. 3, K, L ; Plate XLI, F). 



(11) The daughter colony begins to move slowly, at first with a 

 slight rocking movement, probably due to incomplete co-ordination 

 of the ciliary movement. Soon, however, this rights itself and a slow 

 but steady rotary movement sets in. 



(12) Meanwhile the pore, which may sometimes still be seen even 

 after movement has commenced, has continued to close and finally 

 becomes completely obliterated (fig. 4, D). In healthy colonies no 

 trace whatsoever of the pore can be seen. Zimmermann (1925, 



