1918] Yocum: The Neuromotor Apparatus of Euplotes Patella 385 



as to be controlled by the coordinating centers. In the probable 

 parallel evolution of the two groups, the connection between the neuro- 

 motor apparatus and nucleus has been retained in flagellates but 

 apparently lost in ciliates, with only an indication of such a connec- 

 tion in Diplodinium ecaudatum, while in Euplotes patella no trace 

 remains to indicate that in this highly specialized free-living ciliate 

 the neuromotor apparatus and nucleus are related structures. 



As we look over the literature on Protozoa we are impressed with 

 the change that has come about in the research done on this interesting 

 group of animals. The early works had to do with little else than 

 the classification and the study of external features upon which to 

 base this classification. The works of Ehrenberg (1838), Stein (1859), 

 and Kent (1881) are examples of this kind of work. However, with 

 the improvement of microscopes and better methods of microscopical 

 technique a more intensive study of the animals was begun from every 

 point of view. The cytological phenomena, the minute anatomical 

 structure, life history and economic importance of the Protozoa have 

 occupied the attention of the investigator and many of the most 

 common and earliest know^n organisms have become centers of great 

 interest. 



With all of this study we come to a realization that our old 

 definition that the Protozoa are simple one-celled organisms is in- 

 adequate. A study of the soil amoeba as described by Wilson (1916) 

 shows that even the amoeba which we are accustomed to give our classes 

 in biology as an example of the simplest form of animal life, exhibits 

 a complexity not yet understood, while a study of a form such as 

 Euplotes or Diplodinium shows a complexity unrivalled by many of 

 the IMetazoa, and it seems that the more we learn about them the more 

 complex they become. 



