1922] Rees: The Neuromotor Apparatus of Paramaecium 351 



If we investigate the fibrillar sj'stem of Paramaecium witli the 

 same ideas in mind, we get a more convincing proof than in the case 

 of Diploclinium and Euplotes. The frailness of the fine fibers pre- 

 cludes the idea that they are skeletal or supporting. It is a familiar 

 fact that Paramaecium under a variety of conditions adverse to its 

 normal functioning contracts into a spheroidal body. But, clearly, 

 to get a sphere of an elongated animal the longitudinal axis must be 

 shortened and the transverse axes lengthened. If this change of shape 

 were produced by the neuromotor fibers, those whose direction is 

 transverse would elongate while those whose direction is longitudinal 

 would have to contract. In other words, they would have to function 

 similarly to antagonistic sets of muscles which function in response 

 to nervous impulses. Such coordinated functioning of these extremely 

 fine fibers without innervation is unlikely. 



The morphology also suggests that the fibers are conductile. Their 

 fine branches, which converge from every part of the animal to the 

 motorium, resemble very closely similar branches in metazoan nervous 

 systems. Their connections with the basal granules and trichocysts 

 and with a center suggest these conductile and coordinative fiinctions 

 even more strongly. The set that runs in the cytostome and cyto- 

 pharynx connecting with the same center also suggests coordination. 

 When stained with Mallory's triple connective tissue stain, they take 

 the acid fuchsin. This also suggests that the fibers resemble chemi- 

 cally the nerve fibrils of metazoans. 



The experimental evidence, while less conchisive, is still important 

 in several particulars. The gradient that could be demonstrated was 

 of the type to be expected on the basis of neuromotor function. The 

 transseetions of the cytopharyngeal fibers and resultant lack of 

 coordinated movement of the membranelles are evidence which shows 

 that at least the cytopharyngeal fibers function in the transmission of 

 impulses. 



SUMMARY 



1. A fibrillar system maj' be differentiated in Paramaecium with 

 Mallory's triple connective tissue stain. The fibers are very fine and 

 branch profusely. Thej' take the acid fuchsin and are therefore red 

 by transmitted light. 



2. By means of Heidenhain's iron haematoxylin this very complex 

 system of fibers has been differentiated both in whole mounts and 

 sections. 



