344 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



(1) The first portion of the tube has thin, 

 transparent walls, and is profusely coiled, the coils being 

 quite irregular in their arrangement and forming no 

 definite loops such as are so characteristic of the nephridia 

 of Lumbricus and other types. Its cavity is intra- 

 cellular and ciliated throughout. It is invested by an 

 extremely delicate peritoneal covering, the cells of which 

 are much flattened and possess oval nuclei. 



The first portion of the tube is separated from the 

 second by a curious structure, which, as far as I can tell, 

 has never been described by any other observer as occurring 

 in Tub if ex. It has been figured by Eisen (1885), however, 

 in the nephridia of Spirosperma ferox. He calls it an 

 ampulla, and this name will be used for the corresponding 

 structure as found in Tubifex. Eisen describes the 

 ampulla as an enlargement of the tube of the nephridium, 

 but he does not attempt to give any account of its 

 structure. He does not even venture to express an 

 opinion as to whether it is a permanent or only a 

 temporary structure. Beddard (1895) in his monograph 

 refers to the ampulla in his account of the characters of 

 the family Tubificidae, as occurring in Limnodrilus, 

 Spirosperma ferox and many earthworms. He gives,, 

 however, no account of its structure. 



In Tubifex the ampulla is undoubtedly a constant 

 organ, for I have never failed to find it in any of the 

 specimens that I have examined, whether in sections or 

 by teasing out the nephridium from the living worm. 

 Further, it is present in the nephridium of all segments 

 from the anterior to the posterior end of the body. The 

 ampulla always occurs between the first portion of the 

 nephridial tube and the second, which is characterised by 

 walls of a yellowish colour. The ampulla is usually 

 pear-shaped, although in a few cases it is somewhat more 



