346 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



(PL VII, fig. 48, ci. 1 ). If one liberates .an ampulla 

 with a portion of the tube from the living worm, these 

 cilia exhibit lively movements even for some time after 

 those in the nephridial tubes have become motionless. 

 The wall of the ampulla is not ciliated. 



(2) The second portion of the nephridial tube opens 

 out from the pointed end of the ampulla, and directly- 

 after its origin it is bent back sharply so that it runs for 

 a short distance parallel to the ampulla and the first part 

 of the tube. This part of the tube is characterised by the 

 fact that its walls are somewhat thicker than those of the 

 first part, that they are yellowish in colour, and the cells 

 of which they are formed are very granular. The tube 

 is not much coiled, but is bent on itself two or three times 

 to form well-marked loops which lie approximately 

 parallel to each other and appear to be bound together in 

 a common investing membrane. For the first part of its 

 length this tube is provided with a layer of peritoneum, 

 composed of flattened cells similar to those investing the 

 first part of the tube. These gradually give place to 

 specially modified cells known as vesicular peritoneal 

 cells (PI. VI, fig. 44, v. pt.). These are large, rounded, 

 bladder-like cells with very thin walls. These cells are 

 particularly well seen in the fresh material, but are liable 

 to undergo considerable shrinkage during the processes 

 of killing and fixing. When examined in the living 

 condition, these cells may be clear and devoid of any 

 special solid contents, or they may be filled with minute 

 brownish granules which exhibit active molecular move- 

 ments even after the cell has been dislodged from the 

 wall of the nephridium. 



(3) The third part of the tube is ciliated, is of some- 

 what wider calibre than the first part, and has thin walls. 

 The proximal portion is covered with vesicular peritoneal 



