6 ABT. 4. — EKITAEO NOMURA : 



in my sections. The clitellar hypodermis is notably different 

 from that of the other parts. 



a. Ordinary, or extra -clitellar hypodermis. This layer is 

 generally 5-6 « thick, but near the two ends of the body it is 

 thicker. At the most anterior part the cells are columnar or 

 sometimes fusiform, 10—15 /^ long and 4-5,« across. At the 

 most posterior part they are nearly cubical, measuring 12-13 p, and 

 the cytoplasma shows but little differentiation. 



" At a distance of about 4 millimeters from the (hind) end", 

 writes Athestox, " the body wall merges into a mass of cells 

 lying against the great dorsal blood vessel and constituting the 

 growing zone ; anterior to this, the body wall is marked off into 

 its distinct layers." A similar condition occurs also in L. gotoi. 



Outside the two thickenings at the ends of the body the 

 hypodermal cells are flattened and the cell- boundaries are 

 indistinct, especially in sections stained with eosin. They are 

 apparently supporting cells and the syncytial condition is un- 

 doubtedly a secondary result. 



The cytoplasma of the hypodermal cells is always exceedingly 

 compact. In the anterior and middle parts of the body, the 

 nuclei are more or less elongated ellipsoidal or fusiform, and 

 rarely contain a single nucleolus. Near the posterior end the 

 nuclei are roundish and always contains a large nucleolus. 



The gland cells are large and contain a small amount of 

 feebly staining cytoplasma. They are very abundant in the 

 anterior half of the body, but very few in the posterior, and they 

 do not show any regular arrangement, two cells sometimes unit- 

 ing into one. 



b. Clitellar hypodermis. In life the clitellum is distinguish- 

 ed from the other parts by its glandular appearance. The gland 

 cells are 20-23 fi long and 8-10/.* across, and three well marked 

 stages can generally be observed in fully mature specimens, viz. 

 a highly vacuolated condition, a more or less granulated condition 

 and a condition in which the cells contain many large globules, 

 2 p. in diameter. Besides these gland cells there are, between 

 them, very slender, rather fibrous cells. The nuclei of the clitellar 



