Ii6(i GENERAL HISTORY OF THE INFrSORIA. 



internal germs, which, wlien set free, immediately assumed the special 

 characters of theii' parents (Kleinste Lehenfonn. p. 74). 



To Dr. H. Cienkowsky we owe the latest examination of this subject 

 (J. M. /S. 1857, p. 96). He rejects Stein's theory because, instead of finding 

 Podophrya fixa in company "with VorticeUa microstoma, he met with it in 

 great abundance along with multitudes oi Styhnycliia mytUiis and St. pustu- 

 lata. Ha\^ng watched its process of encysting, he felt '' imable to adopt 

 Stein's view, that the Poclophryce are enclosed in a membrane of which the 

 slender peduncle is simplj^ a tubular process." In fact, he noticed cysts in 

 which the original slender peduncle was appended to the sacculate envelope. 

 He also traced, step by step, from Podophryce, the derivation of the supposed 

 transitional stages between Vorticella-cjfits and Podopliryce, and asserts 

 '^ that they are most certainly not metamorphosed VorticeJIa-cjats, but the 

 commencement of the encysting of Podophryce. Podoplivya-: are not formed 

 out of them ; but, on the contrary, from ihe. latter arise the forms above 

 described, which Stein looks upon as Podophryce remaining at an early stage 

 of development. The metamorphosed contents of older Vorficella-Qjsts, re- 

 garded by Stein as the first commencement of the formation of a Podo- 

 phrya, indicate, according to what I have seen in other infusorial cysts, 

 and to what Stein himself states with regard to VorticeUa microstoma, the 

 commencement of the breaking up of the entire contents into numerous 

 smaller ' swarm '-cells." 



Dr. Cienkowsky's next proceeding was to show the relations of the motile 

 embryo developed from the Podophryean animalcule Stein met with. He 

 encoimtered numerous Acinetce precisely like those figiu'ed by Stein. " Most 

 of these Acinetm were ^vithout peduncles, and had no limitary membrane, 

 although numerous specimens might be seen with a short peduncle and 

 imbedded in a mucoid thick envelope ; and this was especially observed when 

 the Acinetce had lived for about a week on the object-glas.^s (XXIII. 33-39). 

 Although num.erous points of relation exist between these Acineta-iovm^, 

 and Podoplirya fixa (Ehr.), I am nevertheless unable to determine whether 

 thej^ should be regarded as identical, or, with Stein, whether Podophrya and 

 Actinophrys should be considered as the extreme hnks in the morphological 

 cycle of one and the same species (Stein, he. cit. p. 143). The peduncle of 

 an Acineta is a tubular elongation of the enveloping membrane, whilst in 

 the mombraneless Podophrya it is an independent formation. ^\Tien the 

 Podophryce are left in water for a fev,' days upon the object-glass, they form 

 the ver}' characteristic pedunculate cysts ; but, under the same conditions, I 

 have never been able to follow the Acineta-ioTm^ now in question to the 

 formation of cysts ; the former multiply by division, whilst in the Acinetce 

 I have never noticed the occiUTence of that process. "What Stein describes 

 as Actinophrys is really a non-pedunculate Acineta ; the Actinophryce have 

 no tentacles, but setae, though perhaps occasionall}^ some of these setce are 

 capitate. In almost every specimen of the Acinetce in question might be 

 seen rotating a romid or oval embryo, of various size and position, with 

 one or two contractile spaces. This embryo slowly approached the wall of 

 the Acineta, caused it to protrude a little outwards ; and after remaining 

 for a short time quiescent, it slowly made its way through the waU (XXIII. 

 41), and quitted the parent site with the rapidity of hghtning when it had 

 freed about half of itself. This rapidity was so great, that the course could 

 not be traced mth a magnifjdng power of 170 diameters. About five minutes 

 elapsed from the commencement of perceptible motion to the complete libe- 

 ration of the embryo ; and on many occasions I saw two rotating embryos 

 liberated in succession. When the embryo is half out of the parent-cyst, 



