APPENDIX D. xev 



ditions, in the precise nature of the developmental changes 

 or transformations observable amongst these organisms. In 

 fact, Stein himself has described a second mode of origin of 

 embryos within Acineta of Vorticella origin. Such Acinetce. 

 did not possess the ordinary tentacles, though they presented 

 one or two short, closed, tubular processes projecting 

 anteriorly. Within, there was no longer the usual granular 

 contents with a nucleus and contractile vesicle : there were 

 instead, six oval, cell-like bodies, about -gV m length, which 

 seemed to have been developed out of the original con- 

 tents of the Acineta. These bodies were sharply defined, 

 and contained a coarse granular substance with a contractile 

 vesicle. In one of them a ciliated furrow was observed, 

 owing to the presence of which it more closely resembled 

 the usual solitary embryo of the Acineta. Such a multiple 

 development seems to be only an occasional modification 

 of the reproductive process. 



A glance at the other modes of reproduction which have 

 been described amongst the Ciliated Infusoria will astonish 

 the reader by their diversity, and will almost force him to 

 come to the conclusion that there is no definite method 

 of reproduction for any one species. There seem to be, 

 rather, different developmental possibilities by any one of 

 which the reproduction of individuals may be brought about, 

 though the particular mode which is likely to occur on any 

 given occasion appears at present to be wholly uncertain. 

 But the actual process gone through although oftentimes 

 apparently the work of chance would doubtless be capable 

 of predication, if we knew what were the molecular forces at 

 work in organisms of different kinds, of different sizes, and 

 of different ages, and as well the degree and nature of the 

 modifying influence exercised by the ever- varying sets 'of 

 conditions to which these different organisms are subjected, 

 under all their widely differing states of molecular activity. 



VOL. II. g 



