M. E. Claparede on Actinophrys Sol. 213 



parenchyma dilates the integument into the form of a pellucid 

 bladder ; the latter, however, still retains sufficient elasticity to 

 drive the nutritive fluid again into the parenchyma by its con- 

 traction/^ There is, however, no general integument in this 

 animalcule, so that the nutritive fluid cannot be driven back 

 into the parenchyma by its contraction. In his classification 

 Siebold placed Actinophrys amongst his Stornatoda, or Infusoria 

 with a distinct mouth and oesophagus, and close to Prorodon 

 and Leucophyijs amongst the true Ciliata, which are evidently 

 far higher in organization, and some of which possess a well- 

 developed dental apparatus, in addition to a ciliated mouth and 

 oesophagus, whilst there can be no doubt that the natural posi- 

 tion of Actinophrys in the system is near Amoeba and Arcella, 

 amongst the Rhizopoda. 



Siebold ascribes two contractile vesicles to Actinophrys, whilst 

 I have never seen more than one. Several vesicular elevations 

 often occur on the margin, but only one of these is contractile. 

 I have, however, observed two contractile vesicles in several indi- 

 viduals (fig. 2), but in these cases the form always gave rise to a 

 suspicion of fission or of an amalgamation of two individuals {Act. 

 difformis, Ehr.). The presence of a single contractile vesicle 

 does not, however, appear to be universal amongst the Rhizoi 

 poda : I have observed two in Arcella vulgaris. Stein* also has 

 recently called attention to the vesicles in question, and also 

 mentions the existence of two, which furnishes an additional 

 support to Siebold^s assertion. It is still a question, however, 

 whether he saw them in undoubtedly simple individuals. 



It is surprising that Kolliker, who was acquainted with Sie- 

 bold^s observations, should have characterized them as incorrect> 

 and as arising from an illusion. According to him, Siebold had 

 mistaken accidental expansions and contractions of the substance 

 enclosing the vacuoles, in which the latter were persistent, for 

 phsenomena indicating the existence of contractile reservoirs. 

 This, however, is not the case ; the size, the unchanging position, 

 and the regular expansion and contraction of this organ, resem- 

 bling the systole and diastole of a heart, will prevent its being 

 confounded with a vacuole. That Kolliker should have over- 

 looked it is particularly unintelligible, as the phsenomenon is 

 immediately presented by nine out of ten specimens of Actin- 

 ophrys: I have often admired this charming spectacle for hours, 

 without observing the least irregularity. 



^ -x- -K- -Jf -x- -Jf ■)«■ 



Before quitting the consideration of the contractile vesicle, we 



• * Die Infusionsthiere, auf ihie Entwickehmg untersucht von Steiiri 

 Leipzig, 1854. 



