364 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



v.d.l). Ciliary action does not occur by any means 

 regularly in this part, for it is often completely in 

 abeyance, but the cilia are so long that they can be easily 

 seen, even when they are motionless. 



In the wall of the ciliated portion of the tube we can 

 recognise the following layers: — (1) Ciliated epithelium, 

 (2) Muscular layer, and (3) Peritoneum. 



The ciliated epithelium forms the innermost layer of 

 the wall of the duct and is composed of a large number of 

 flat, annular or ring-like cells piled very regularly on 

 one another. Each cell is perforated in the centre by 

 a large, rounded lumen, about 42 n in diameter, the wall 

 around it being comparatively thin. A continuous tube 

 is formed by the regular arrangement of the cells and by 

 the fact that the cavity is pierced in exactly the same 

 position in all the cells (PL IV, fig. 20a). Each cell 

 possesses a single, elongated, somewhat spindle-shaped 

 nucleus which may extend almost half way round the 

 cell (PL IV, fig. 19a). It is pointed at both ends and 

 somewhat broader near the middle, where it exhibits a 

 well-marked, rounded nucleolus. The inner edge of each 

 cell is plentifully provided with cilia which are rather 

 longer than the radius of the cavity, and have a somewhat 

 spiral arrangement (PL IV, fig. 19a, ci). The cells 

 themselves appear to be embedded in a structureless 

 matrix which stains with plasma stains and forms an 

 extremely delicate layer right round this part of the duct. 

 The centre of the tube is usually occupied by a dense mass 

 of spermatozoa, which in the living condition can be seen 

 travelling down the tube. The muscular layer is but 

 feebly developed in this part of the tube. It consists of 

 a single layer of longitudinal muscle fibres which are 

 disposed at equal distances around the tube (PL IV, 

 fig. 20a; Z.ra.). They do not pass straight down the wall 



