DERIVED ORGANIZATION 131 



known, nevertheless the literature contains many references to 

 myonemes in the several species. Distinct fibrils in these hypo- 

 trichs which Engelmann regarded as nerve-like in function, have 

 been interpreted in the main as supporting or contracting elements 

 (Maupas, Biitschli, Schuberg, Maier, etc.). Prowazek worked them 

 out in some detail in the case of Euplotes harpa and Griffin (1910) 

 in the case of E. worcesteri, both observers regarding them as con- 

 tractile in function. Yocom has studied them more recently in 

 Euplotes patella and a complex system, comparable with that of 

 Diplodinium ecaudatum is described. A definitely staining bilobed 

 mass of differentiated protoplasm which Yocom identifies as a 

 motorium is situated in the ectoplasm near the right anterior angle 

 of the triangular peristome (Fig. 72, m). 



From one lobe of this mass a set of five prominent longitudinal 

 fibrils which seem to emerge as a single strand, run to the bases of 

 the five anal cirri near the posterior end (a. c); from the other lobe 

 a single fibril passes along the inner margin of the anterior lip and 

 down the left side of the peristome closely following the bases of the 

 frontal and peristomial membranelles. In the anterior lip it gives 

 rise to a simple network of branching fibrils (Yocom). The other 

 cirri of the ventral surface are not thus connected with the motorium, 

 and each appears to have an entirely independent set of fibers which 

 run into the endoplasm and disappear in different directions. 



Yocom attempted, rather unsuccessfully, to homologize the 

 motorium with the blepharoplast of flagellates; until further obser- 

 vations are forthcoming in regard to the activities of this structure 

 at different periods of cell life it seems more expedient to regard the 

 motorium as a structure peculiar to the ciliates than to add it to 

 the already over-burdened conception of the blepharoplast. 



The only direct evidence of the physiological nature of the neuro- 

 motor complex is furnished by Taylor's micro-dissection experi- 

 ments with the same organism, Euplotes patella (Fig. 72). Cutting 

 the fibers connecting the anal cirri with the motorium had a notice- 

 able effect on the normal reactions of creeping, swimming and 

 turning, while severing the membranelle fiber led to character- 

 istic irregularities in the usually coordinated activities of the mem- 

 branelles and to abnormal spiral revolutions while swimming. 

 Destruction of the motorium, finally, resulted in uncoordinated 

 movements of the membranelles and of the anal cirri. This evi- 

 dence, excellent as it is, rests upon an exceedingly delicate technique 

 and upon the personal interpretation or estimation of minute differ- 

 ences between normal and induced reactions. It is a line of work, 

 however, which invites further research and promises fruitful results. 



