288 Mr. H. J. Carter on the Fresh- and Salt-ivater 



Separation then takes place, and the tentacula again begin to 

 appear (b, c), when, in their turn, the cilia are retracted, the 

 tentacula fully reproduced, and, finally, the young half (d) as- 

 sumes the spherical form of the older one or parent (a). 



In the second instance, the young Acineta (for my sketches 

 of this happen to be taken from the young of A. tuberosa) leaves 

 the parent with a wreath of cilia round its smaller extremity 

 (fig. 11 a), in such a state of activity that it is difficult to follow 

 it to its resting-place. This, however, soon takes place, and if 

 successfully kept in view, the cilia will be found, on its having 

 become stationary, to present a curved form, which has been 

 occasioned by the centripetal force communicated to them by 

 the young Acineta which they have been rotating in the oppo- 

 site direction (b). The cilia then regain their straightness, and 

 assume a radiated form, on which they begin to be retracted (c). 

 After this, the tentacula appear (d) ; and finally the latter are 

 fully extended, and the cilia withdrawn (<?). This would be the 

 end of the series in Podophrya ; but Acineta tuberosa being a 

 stalked form, its final development is not completed until this 

 has been attained. 



By some it might be said, as before stated, that the cilia and 

 tentacula are as much extemporized as the stomachal spaces and 

 digital prolongations of A?7ioeba, while others would adhere to 

 the opposite view. It is almost as difficult to conceive one as 

 the other — that is, how vibratile cilia and tentacula, organs of 

 totally different forms, and endowed with totally different func- 

 tions and movements, can exist and 'be made to appear and dis- 

 appear, with less complicated machinery than that which must 

 necessarily accompany similar organs in animals much higher 

 in the scale of development. 



Perhaps there are no phenomena more remarkable among the 

 Rhizopoda, in themselves or for the facts which they establish, 

 than those just described, and none more easily followed and 

 witnessed when the forms of Acinetina mentioned have been 

 obtained for observation ; for while some are continually under- 

 going duplicative division, the others are as continually sending 

 forth a young one. 



They are extremely restless animalcules in all respects, some- 

 times hardly being encapsuled before they burst forth again, 

 and then become encapsuled a second time before the whole of 

 their substance has left the first capsule (fig. 10 e). Both these 

 forms of Podophrya also may be stalked (10 c). 



For other observations on the Acinetina, containing views 

 respecting their parasitic nature, &c, see my " Notes and Cor- 

 rections" (Annals, vol. viii. p. 281, 1861). 



