364 GENEEAL HISTORY OF THE INFIJSOEIA. 



lobe, resembling somewhat a retracted rotary organ, Avhilst the fissure ex- 

 tending inwards indicates the alimentary tube. 



There is yet another apparent mode of embryonic development in the 

 Acinetce of VorticelUna described by Stein, which occuiTed in some specimens 

 not provided with tentacles. In place of these, one or two short closed 

 tubular processes extended from the fore part of the animalcule; of the usual 

 granular contents scarcely a trace remained ; and the nucleus and contractile 

 space had entirely vanished. The membrane of the enclosed body, thus 

 deprived of its ordiuary constituents, contained, in their room, six elongated- 

 oval cell-like bodies, J^'" long, w^hich seemed to have been developed at 

 the cost of the contents of the original Acineta. These structures had a 

 sharp outline, and contained a coarse granular substance and a contractile 

 sac. They seem to develope into embryos ; for in one case a ciliated furrow 

 was observed, assimilating the being to the more usual embryos of the 

 Acinetce. Probably the ^cmefa- condition of the Vag'inkola is terminated 

 in this manner, after developing for a period embryos according to the plan 

 above mentioned, by the final breaking up of the nucleus into several large 

 germs. 



In addition to the species described. Stein believed he made out the 

 Acineta-^i?iiQ of several other species of Vorticella, of EpistiiVis, and Oj^ercu- 

 laria (XXX. 1-4), as well as of ZootJiamnmm, Ophrydimn (XXX. 5-8), and 

 Sph'ocliona (XXX. 18-26). However, sufficient details have been given to 

 illustrate the presumed fact in the developmental histoiy of the Ciliated Pro- 

 tozoa ; and we must refer those of our readers desii'ous of more fully testing 

 the views of that most excellent observer, to his often- cited work, ' Die 

 Infusionsthiere auf ihre Entwdckelungsgeschicte,' Leipzig, 1854. More- 

 over, the several new forms of Acinetina he has pointed out A\all be found 

 referred to in the general histoiy as well as in the systematic views of that 

 group. 



It is now incumbent on us to review the opinions of other naturalists upon 

 this remarkable and interesting hypothesis. A few have accepted it, among 

 whom are Mr. Busk (as we gathered from his lectures at the College of 

 Sui'geons in 1857) and Mr. Carter. The latter has the following remarks 

 on the subject {A. N. H. 1856, xviii. p. 237) : — "I could not discover an 

 elongated nucleus, as Steiu has figiured, in the Amoehce and Acinetce, which I 

 saw developing young VorticeUce, the fonner in plurality (one to three) and 

 the latter singly : if present in the Amoebous form, it was circular, and if in 

 the Acinetce, undistinguishable from the general ' granulation.' Again," he 

 goes on to say, " where are these transformations to end ? Into what kind 

 of Rhizopods do the sheathed VorticeUce pass ? How many of the fresh- 

 water Bhizopocla are alternating forms of VorticeUce ?" At the time of his 

 writing the above, Mr. Carter had not seen Stein's latest work, which would 

 have resolved some of the doubts and queries expressed. Thus, the Gennan 

 naturalist finds the nucleus, if elongated and band-Like in the encysted being, 

 to become orbicular or oval when in an ^mie^a-state, and points out that acetic 

 acid wiU reveal this organ when obscui-ed by the granules of the interior. 

 Moreover, his later researches have been extended to sheathed VorticelUna 

 or Ophryclina — for instance, to Vaginicola, of which we have given the par- 

 ticulars. However, it is very important to obtain Mr. Carter's statement 

 that he has seen young VorticeUce developed from Acinetce and Amoehce, — in- 

 tending by the latter, we apprehend, Acinetce without tentacles and capsule, 

 and not the simple Amoehce commonly understood by that term. 



The objectors to the hypothesis are by far the more numerous. The emi- 

 nent physiologist .Johannes Midler, to whom Stein showed ActinopTirys and 



