12 



AKT. 4. — EKITAEO NOMURA : 



The typical chloragogue cells are club-shaped, with the 

 thicker end directed towards the body cavity, and the cytoplasm 

 is thin. The nuclei always lie in the distal half of the cells and 

 contain each a large central nucleolus. The cells invariably con- 

 tain chloragogue granules and vacuoles. The chloragogue granules 

 are perfectly round and of a blackish brown colour in life. In 

 dark coloured specimens the cells are richly filled with these 

 granules. The granules are large and stain well with the fuchsin 

 of Malloey's method and Heidenhatn's haeniatoxylin. They are 

 of uniform size and measure 1.3 j« in diameter. The vacuoles are 

 of different sizes, some being half as large as a cell. If a single 

 large one is present in a cell, it always occupies the proximal 

 half. In life the whole vacuole is filled by a fat or oil 

 globule. 



4. Septa, Septal sacs and Amœbocytes. 



Fig. 4. 



Z. rjoloi. Diagram showing the septal muscles, bw — body 

 ■wall, int — intestine, nc — ventral nerve cord, rnf — muscle fibres. 



The cœlom is very 

 spacious and traversed 

 by the intersegmental 

 septa, which begins at 

 II I/I V. In the anterior 

 part of the body the 

 septa are always more or 

 less funnel- shaped, with 

 the smaller end directed 

 posteriorly, especially 

 in the fore part of the 

 genital segments. The 

 septa X/XI and XI/XTI 

 are often exceedingly 

 thin, and are apt to 

 be overlooked in fresh 

 specimens. 



Each septum con- 

 sists of three layers. 



