1918] Yocum: The Neuromotor Apparatus of Euplotes Patella 381 



(1913) has shown, such a function could scarcely be attributed to the 

 system of fibers. Then, too, their distribution in relation to the motile 

 parts of the organisms is like that in Diplodinium, so that it would 

 seem that a function of conduction and possibly contraction to a 

 slight degree, is more nearly correct, as Sharp (1913) has indicated 

 for Diplodinium. 



Of all the above works mentioned, with the exception of the works 

 on Stylonychia (Englemann, 1880), Stentor (Neresheimer, 1903) and 

 Diplodinium (Sharp, 1913), none contains any suggestion of nervous 

 structures, but all seem to consider the function of the fibrillar sys- 

 tems to be that of contraction or support. 



The above brief comment on forms in which there are fibrillar 

 structures suggestive of neuromotor apparatuses shows us that in all 

 of the orders of the Ciliata there are to be found in connection with 

 the basal granules of the cilia, cirri, membranelles and undulating 

 membranes, distinct fibers which lead out into the cytoplasm of the 

 cell. In some cases, as Didinium, Euplotes harpa, and Euplotes wor- 

 cesteri, there is a distinct indication that the fibers may converge to a 

 definite body such as is found in Euplotes patella and Diplodinium 

 ecaudatum. In others, as Stylonychia, the fibers have been shown to 

 run out into the endoplasm and fade out. Whether this is the case 

 or not further investigation alone can demonstrate. At least such 

 suggestions open up a field which is as yet little developed, and which 

 will perhaps yield the richest fruits when the work on prepared slides 

 is supplemented by work of an experimental character. 



The Neuromotor Apparatus of Flagellates 



The term neuromotor apparatus has been used also to denote a 

 structure found in flagellates, and there has been worked out within 

 the last few years a series which indicates a progressive evolution of 

 this structure in this class of Protozoa. It will be necessary to go 

 over this series briefly in order to see whether or not the term neuro- 

 motor apparatus as applied in the study of certain flagellates indi- 

 cates a structure homologous to that described in ciliates. 



The first form in the series is Naegleria gruheri, a soil amoeba which 

 under certain conditions temporarily changes from its rhizopod form 

 to that of a biflagellate organism. In her work on this animal Dr. 

 Wilson (1916) discovered a very primitive neuromotor apparatus. 

 Flagella arises from a blepharoplast which grows out from the central 



