CAiNfEuox. — Xe/)/i rich' urn of Manridrilus vosae Hi'(hl(ii(I. 



185 



funnel is ciliated tliiougliout : not only the luar^iiialfi. hut even the central 

 cell, as well as the epithelial cells sm-roundini)' the lumen m the proximal 

 part, bear cilia. The nephi'ostomial duct from the funnel to its point of 

 entrance into the anterioi- fold is finely ciliated. From sections, these cilia 

 appear to be in two rows, but 1 could not ascertain the exact arrangement 

 from a living specimen. The narroA^- canal has few ciliated regions, and 

 these are confined to the dorsal lobe. In the inner narrow canal [a.i) cilia 

 were observed moving in three shoi't lengths as shoAvn in fig. 8, the 

 direction of the excretoi'v current being tOA\ards the anterior fold. No 

 other cilia could be seen in the narrow duct. The bridge canal is ciliated 

 from its commencement up to the ampulla (fig. 8), the cilia being directed 

 towards the ampulla. The cilia in this canal form the chief means of dis- 

 tinguishing it and tracing its direction and limits. At the sharp bend 

 (fig. 8, B), where the narrow tube is continued into the bridge canal, ai-e 

 two peculiar stnictures ; they have the form of two combs of cilia (fig. 1), 

 co), which lie almost at right angles to the course of the tubule. They aie 

 formed, as can be seen from the figure, of fused cilia, some of which are free, 

 or have become frayed out to form the teeth of the comb. Their function 

 is evidently to create a stronger current than could be given by se])arate 



am,p. 



Fig. K). 



Fig. 9. — Knlaraod drawing of the i-oiuinoiiffincnt "f the bridge canal (/>), sliowing 

 the combs of cilia (ro) lying across tiie entrance to the canal. 'I'he arrow 

 indicates the conrse taken by the excretory vesicles. 



Fig. 10. — Enlarged view of the ap(>x of the s]nir, showing the entrance of the bridge 

 canal into the atnpulla. 



cilia at the sharp turning : and on this account they may be compared, 

 I think, with the membranella ov undulating jueinbrane of Paiainoeciinii. 

 which is often frayed at the edge. 1 thought at first that they could be 

 compared to the "' undulating Structuies c(mrposed of bundles of long cilia- 

 like filaments "" of MoitHir/uster (iraiidis (15, p. 339), but these, though placed 

 obliquely across the lumen of the excretory duct, are attached at both ends, 

 and have no comb-like appearance : while the waves of undulation work 

 in the direction of the current — i.e., from the nephrostome outwards. 



The combs of MaotidriJu.s work unceasingly with an undulation along 

 the comb — i.e.. across the current — while the cilia foi-ming the teeth work 

 strongly backwards and forwards, sweeping the contents of the tube on 

 towards the nephridiopore. The inner' narrow canal {a, fig. 9) contains 

 excretory droplets oi' globules {ex.v), and as these arrived at this point they 

 were seen to be giadually forced round the bend by the action of the combs. 

 The cilia worked moi'e energetically on coming into contact with the dro])- 

 lets, while the imdulating motion also became brisker. It was some time 

 before the larger globules were forced romid, the smaller ones being moie 

 easily disposed of and brought round by the sweep of the cilia into the 



