INFUSORIAL ANIMALCULES. 



119 



Diijardin also states that lie has been unable to recognize all the 

 genera of Ehrenberg, and believes that the Microglena, Phacelomonas, 

 Glenom(yrum and Doxococcus appertain to another family, that the 

 distinction between the genera Polytoma and Uvella, is erroneously 

 deduced from the supposed fission of Polytoma in two opposite di- 

 rections, and the periodical grouping of JJvella. He thus reduces 

 the genera of Ehrenberg, to four in number, viz Manas, Ifvella, 

 Chilomonas and Bodo, the last comprehending in part his Sexamita, 

 Am2)himonas, and Cercomonas. The subjoined table represents the 

 distribution by Dujardin, of the 



MO^^ADINA. 



f Moveable in its entire 



A Single 



Flagclliform •< 



Filaraeut. 



Proceeding from the anterior I ^l^"^"! Monas. 



Isolated 



Aggregate 



„„» ;,„ ^ Thickened, and move- 



'^^^'^^"'y- ] able only toward.s 



L the e.xtremity Cyclidium. 



Proceeding: obliquely from behind an anterior pro- 

 longation Chilomonas, 



' A second filament or lateral appendage Amphimonas. 



A second filament, or posterior appendage Cercomonas. 



Two equal filaments, terminating the rounded angles 



of the anterior extremity Trepomonas. 



Four equal filaments in front, two thicker behind. . . Hexamita. 



A second filament proceeding from the same point 

 as the flagelliform filament, but thicker trailing and 

 retractile Heteromita. 



A filament and vibratile cilia Trichomonas, 



Groups always free and whirling Uvella. 



Groups fixed to the extremity of a branching polypdom Anthophya. 



Several 

 Filaments 



As to the mode of propagation of the Monadina, Dujardin states 

 that he has never witnessed the spontaneous fission described by 

 Ehrenberg, but thinks it more probable that their multiplication 

 takes place by the separation of a lobe, or of the termination of an 

 expansion. 



"We may gather, from the following summing up given by 

 Dugardin, after his general indications of the genera of Monadina, 

 what value he assigns, in the present state of knowledge, to any 

 attempted classification of such minute creatures. He remarks, 

 " But these generic distinctions are entirely artificial, and simply 

 intended to facilitate the naming of Infusoria one may have met 

 with, in such and such an infusion, and which better known, may 

 prove in some instances but varieties of a single species." (Hist. 

 Infus. p. 273.) 



