CLASSIFICATION OF THE INFUSORIA. 197 



maintained by Stein to be metamorphic conditions of various Vorti- 

 cellidae, while the latter one comprised only the family group of the 

 Peridiniidae. 



The classification of Diesing, a compiler and not an independent inves- 

 tigator, of the present group of organisms, is reproduced (see page 206 et 

 seq.) so far only as relates to the Flagellate series, he exhibiting a keener 

 appreciation of their most salient diagnostic characters than had been dis- 

 played by any previous authority. Taking on trust the dictum of Ehren- 

 berg, this writer, unfortunately, fell into the error of ascribing to every 

 member of this group the possession of a distinct oral aperture, which 

 structure is abundantly shown in this manual to have no definite existence 

 among a very considerable series, Diesing's peculiar views respecting the 

 affinities of certain of the Ciliata and Protozoa generally have been referred 

 to at length at page 25 of Chapter I. 



Professor Stein's system, which may be cited as representing the most 

 advanced views of Continental biologists with reference to the classification 

 and taxonomy of this highly interesting organic group, demands more 

 extensive notice. In its concrete form, as reproduced at pages 209 and 210, 

 such a tabulated list has not yet appeared, it being composed of the scheme 

 relating to the Ciliata only, embodied by Stein in the second volume of his 

 'Organismus der Infusionsthiere,' published in the year 1867, to which is 

 prefixed the list of families with included genera contained in the preface 

 to his recently issued volume, illustrative of the Flagellata, published at the 

 close of the year 1878. As previously remarked, no diagnoses or descrip- 

 tive accounts of the numerous families, genera, or species so abundantly and 

 admirably figured in this volume have as yet appeared, nor is any attempt 

 made to subdivide the series as a whole into subordinate sections or orders. 

 Critical remarks can consequently under present circumstances be passed 

 only upon his proposed family grouping of the respective genera. In this 

 connection, exception is here taken, in the first instance, to Stein's admission 

 among the ranks of the Flagellate Infusoria of the several family groups 

 of the Volvocina, Chlamydomonadina, and Hydromorina, whose represen- 

 tatives, with one or two exceptions, must undoubtedly, as first insisted by 

 Von Siebold, be referred to the vegetable kingdom. Their claim for admis- 

 sion to Stein's scheme is, while the inevitable sequence of the very shallow 

 basis upon which he considers the proof of their animal organization to be 

 substantiated — that only of the possession of a nucleus and contractile 

 vesicle — by no means supported by the verdict of such modern authorities 

 as Colin, Sachs, and Pringsheim, by all of whom Volvox and its allies more 

 especially are relegated without hesitation among the lower Algals or Pal- 

 mellacese. The broad distinction insisted upon by these writers as subsist- 

 ing between unicellular plants and animals is identical with that already 

 submitted by the author at page 36 et seq., namely — the capacity of such 

 animal forms to incept and digest food-matter in its solid state, and the cor- 

 responding absence of such an ingestive faculty in all vegetable organisms. 



