Mr. H. J. Carter on the Organization of Infusoria. 287 



the slothful Miizopod. Besides, the Fact that the gemma of 

 Acineta does not pass into a Vorticella having now been deter- 

 mined leaves us without a single instance of probability that 

 Vorticella should be in any way developed from Amoeba. 



Having made this explanation, let us for a moment turn our 

 attention to the other point of Stein's theory, viz. the trans- 

 formation of Vorticella into Acineta, also witnessed by Udekem 

 (Ann. des Sc. Nat. ix. p. 321, Zool. 1858). 



Respecting this metamorphosis, much doubt, and even denial, 

 has been expressed ; but although all have not had the good 

 fortune to witness it, yet it seems to rest now on evidence too 

 good to be questioned, although perhaps the right interpretation 

 has not been given to it by those who have seen and described it. 

 ■ Now, no one can have observed a number of spherical Acinetce 

 (Podophrya fixa, Ehr.) adhering to the surface of Paramecium 

 aurelia and carried about with it, without connecting it with the 

 parasitic Rhizopods, which, attaching themselves to Chlamy do- 

 coccus, Eudorina elegans, and the like, in a globular form, already 

 convey their germs into their interior, and begin to devour the 

 substance of their host while the latter are yet actively swimming 

 through the water, and without thus coming to the inference 

 that both organisms are of the same nature. 



Again, no one can at first witness the change which, almost 

 like a " dissolving view/' takes place in the protoplasm and 

 chlorophyll of Chlamy do coccus, Eudorina, and that of the cells of 

 Algas generally, during which these pass from their original form 

 into that of a Rhizopod, without inferring that the form pro- 

 duced is merely another one of that which preceded it, and no 

 absolute change. Hence my description of the fancied passage 

 of the vegetable protoplasm into Actinophrys, to which I shall 

 more particularly allude by-and-by (Ann. Nat. Hist. vol. xix. 

 p. 259, 1857), and which at the same time also I classed with 

 that of Vorticella into Acineta. 



Seeing, then, the great analogy, if not real identity, that exists 

 between the nature of these organisms, I would suggest that 

 the transformation of Vorticella into Acineta may be of the same 

 kind as the passage of the vegetable protoplasm into rhizopodous 

 forms — that, in fact, the germ of Acineta, like the egg of the 

 Iclmeumonidse among Insects, becomes encysted with the Vorti- 

 cella, eats up its host, and comes out an Acineta, as the larva of 

 the Ichneumon-fly, which is hatched in the chrysalis of one of 

 the Lepidoptera, lives upon its host, and comes out of the 

 cocoon, not a butterfly, but a wasp. 



That the stalked Acineta upon Epistylis are parasitic can easily 

 be seen, because they are not upon the ends of the dichotomous 

 branches of their host, but fixed to them by single smaller stems 



