26 



PROTOZOA. 



were certainly shown to exist, which, however, can all be referred 

 to differentiation of the body of the cell. This view is supported 

 by the more recent work of Biitschli and Maupas, who have 

 shown that in their reproduction these animals resemble other 

 Protozoa: that is to say, that the whole body participates in the 

 reproductive fission, that the parent disappears in the offspring, and 



FIG. 21. a, Cercomonas intestinalis; 

 b, Tricliomonas vaginalis (after 

 Leuckart). 



FIG. SLTridumwas 



batraclwrum (after 

 Stein). Us undu- 

 lating membrane. 



FIG. 23. Oikomonas termo 

 (after Biitschli). n nu- 

 cleus ; Cv contractile 

 vacuole ; Nv vacuole 

 which takes up the 

 food (oral vacuole). 



that special conjugating cells of the 

 nature of ova and spermatozoa are not 

 formed. Maupas especially, by follow- 

 ing the history of the individual result- 

 ing from conjugation, has definitely 

 established the fundamental distinction 

 between conjugation and reproduction, 

 and has thrown a flood of light upon 

 the meaning of the whole phenomenon 

 of conjugation. 



The outer boundary of the body is 

 usually formed by a cuticle a delicate 

 transparent membrane, the surface of 

 which is beset with vibratile and 

 moving appendages of various kinds. 



In the smallest Infusoria i\& Mastigophora, we find only one or 

 two long whip-like cilia; while the more highly differentiated 

 Ciliata are usually richly provided with cilia. Finally, in the 

 Acinetaria the young forms have cilia, and the adults a number 

 of delicate tentacle-like processes, which either end in suctorial discs 

 or are pointed. 



FIG. 24. Gonium perforate (after 

 Stein). The colony a from above, 

 b from the side. 



