CILIATE FIBRILLAR SYSTEMS 221 



the body groove overlying the neuroid, as produced by the contraction of 

 the myoneme under the neuroid. The attachment of the pelHcle to the 

 neuroid and the latter, in turn, to the myoneme would, upon contraction 

 of the myoneme, cause an ingrooving of the pellicle. 



Studies on the hypotrichous ciliates yielded apparently the first re- 

 corded example of fibrils directly associated with ciliary locomotor 

 organelles. Engelmann (1880) traced such fibrils from the bases of the 

 marginal cirri of Stylonychia "nach der Mittellinie des Leibes." He 

 postulated for these fibrils a conductive function in transmitting im- 

 pulses, as in nerves of higher animals, from the ventral region of this 

 hypotrich to the cirri, the movements of which might thereby be 

 regulated. 



Engelmann's interpretation was formulated entirely by analogy and 

 he offered no substantial evidence to support it. It seems to have been 

 generally rejected by his contemporaries. Maupas, who three years later 

 (1883) described similar fibrils in E. patella var., said, in a brief foot- 

 note (p. 622) concerning his own findings: "Quant a la signification 

 physiologique de ces racines ciliaires, j'avoue ne pas la connaitre." And 

 with reference to Engelmann's discovery of "fibrilles nerveuses" in 

 Stylonychia myttlus, Maupas adds: "Je ne sais comment concilier des 

 interpretations aussi divergents." Biitschli regarded Engelmann's inter- 

 pretation as untenable and proposed, on equally meager evidence, a 

 contractile function for these fibrils. Maier (1903), who attributed a 

 contractile function to the basal fibril associated with the basal lamellae 

 of membranelles in Stentor, concluded that the lateral cirri fibers in 

 Stylonychia were "required" for the support of these cirri. 



Prowazek (1903), on the other hand, suggested that the anal cirri 

 fibers which he found in E. harpa might perform the dual functions of 

 contractility and conductivity. He noted, however, that E. harpa could 

 move each anal cirrus independently and could flex the tip of these cirri 

 quite at will. He observed, moreover, that a detached anal cirrus might 

 continue its contractions for a time. These important observations have 

 apparently been overlooked by later investigators. 



It will be recalled that Grifl&n (1910) compared the anal cirri fibrils 

 of E. ivorcesteri, which he found and described, with myonemes whose 

 number might have become reduced phylogenetically during reduction 

 in the hypotrichs's rows of cilia. He pointed out a difficulty in this 



