DENDROCOMETES PAKADOXUS. 357 



iuxtaposifciou of tlie nuclei in tlie individual cases examined. 

 It may also lead to the discovery of other cases of the 

 conjugation of meganuclei in the Acinetaria and in the 

 Ciliata. 



As a general result of these considerations^ it seems to me 

 that Ave must either abandon the use of the expression 

 " unicellular organisms " in our definition of the Protozoa, 

 or else very largely extend the meaning of the term " cell." 

 In the recent text-books published by Sedgwick and b}^ 

 Shipley and Macbi-ide, the former course is adopted; but 

 Long, in his ' Lehrbuch der vergleichenden Anatomie/ 2iid 

 edition, 1901, says, '' Die einfachsten Organismen, die 

 einfachsten Thiere (Protozon), und die einfachsten Pflanzen 

 (Protophyta) sindweiter uichts als selbstaudig und unabhangig 

 lebende Zellen." 



The body of a Paramoecium or of a Dendrocometes is no 

 more a single independent cell than is the embryo sac of 

 an Augiosperm plant. 



If we are prepared to extend the use of the term cell 

 so as to include all structures that are bounded by an 

 undivided cell wall or cell boundary, then the expression 

 "unicellular" may still be applied to the Protozoa; but, in 

 my opinion, the inconvenience of such a course would far 

 exceed the advantages it might present. 



List of the Principal Papers referred to in this 

 Memoir. 



1. O.BuTSCiiLi. — " Ueber den Dendrocometes paradoxus," etc., 'Zeits. f. \v. 



Zool.,' vol. xxviii., 1S77, p. -±9. 



2. 0. BiJTSCHLi. — " Infusoria" in Bronn's ' Tiiierreicli,' 1889. 



3. L. CuENOT. — ' Evolution des Grcgarines celoniiquc du Grillon doniis- 



tique," 'C. R.,' cxxv, p. bi. 

 3a. L. CuENOT. — ' L'Epuration nuclcaire au debut de I'Ontogeuese,' t. c, 

 p. 190. 



4. E. Claparede et J. Lachmanu. — 'Etudes sur les Infusoires,' Geneva, 



1857-18GO. 



VOL. 45, PART 3. — NKW SEUIES. BB 



