2 8 BIBLIO GRA PH V. 



the sponges, the result of the author's investigations has, as recorded in the 

 chapter hereafter devoted to this special subject, been the accumulation of 

 additional data of the most substantial character in support of the pre- 

 viously suggested affinities. 



Among the numerous contributors towards a more extended knowledge 

 of the Infusoria as yet unreferred to, may be mentioned, more especially in 

 association with the Ciliata, the names of Wrzesniowski, Richard Greefif, 

 and Edouard Everts, and with the Flagellata, that of L. Cienkowski. 

 Among the former Greefif is exceptionally prominent, he being led, through 

 his discovery in the Vorticellidae of a more complex pharyngeal apparatus 

 and muscular system — hereafter described — than had hitherto been attri- 

 buted to them, to adopt a Coelenterate interpretation of infusorial structure 

 closely identical with that first enunciated by Claparede and Lachmann. 

 Cienkowski's investigations are especially interesting, as being productive of 

 a masterly account of the structure and developmental history of Noctihica, 

 which is definitely shown by him to be intimately related to the more 

 ordinary Flagellata. 



Associated with those that take a prominent position within the present 

 decade as expositors of the structure and afifinities of the Infusoria, Professor 

 Ernst Haeckel's name is eminently noteworthy. In his admirable essay, 

 " Zur Morphologic der Infusorien," published in the 'Jenaische Zeitschrift,' 

 Bd. vii. Heft 4, for the year 1873, this gifted biologist brings forward, 

 beyond question, the most powerful evidence in support of the unicellular 

 composition of these protozoic organisms adduced since the first conception 

 of the theory by Carl von Siebold, in the year 1845. The lucid exposition 

 given by him of the general morphology, reproduction, and developmental 

 aspects of the higher Infusoria, may be further said to constitute one of 

 the most complete accounts of this interesting group yet produced. It 

 must be noted here, however, that Professor Haeckel in his essay admits 

 to the rank of true Infusoria those representatives of the class only that 

 are here collated under the title of the Ciliata, the equally or even more 

 abundant and important class of the Flagellata being dismissed as con- 

 taining an association of doubtful forms, chiefly referable to the vegetable 

 kingdom. The great progress that has been made since the date of this 

 essay in our knowledge of the last-named group will no doubt, however, 

 exert its influence, and reconcile Professor Haeckel to its occupation of a 

 position in the animal scale contiguous to that conceded in his earlier 

 classificatory systems to the Ciliata. 



Comparatively insignificant as has hitherto been the sum of contribu- 

 tions to our knowledge of infusorial life and structure by English investi- 

 gators, and as is conspicuously evidenced on reference to the Bibliogra- 

 phical list appended to this volume, a brilliant exception is furnished in 

 connection with the names of Messrs. W. H. Dallinger and J. Drysdalc, 

 whose joint investigations arc recorded in various numbers of the 'Micro- 

 scopical Journal' extending through the years 1873 to 1875. The chief 



