50 ART. 4. N. YATSU : 



of the disc. It takes a strong orange-G stain. No nucleus is 

 present in it. One of these curious bodies is represented in Fig. 

 82, PI. VI., (coloured yellow, half orerlapping the right obi. int.). 

 In larvae older than that of the 6 p. c. stage I could not detect 

 this element at all. Its nature is quite unknown to me. 



<j. Alimentary Canal. 



During the 4 p. c. stage the alimentary canal has differ- 

 entiated into several parts (vide. p. 39.) viz : the oesophagus, 

 liver ( = oral part of the stomach, Brooks '78), mid-gut ( = Mittel- 

 darm, Blochmann ; , oo=intestinal part of the stomach, Brooks), 

 and intestine ( = Enddarm, Blochmann). From the 5 p. c. stage 

 onward the chief changes concerning the alimentary canal consist 

 in the constriction of the liver into lobes. 



In life the oesophagus and intestine are of a very light 

 yellow color, while the liver is tinted a little darker brownish 

 yellow. The mid-gut, on the contrary, is transparent and almost 

 colorless. 



The oesophagus (PI. V., Figs. 77-80, PI. VI., Figs. 81, 

 83-8o, and PI. VIL, Figs. 91-95, œs.) in its first part takes a 

 nearly horizontal course, and bending at almost a right angle, it 

 reaches the stomach a little posterior to the ventral ganglion (yt. 

 gn.). It is composed of tall columnar epithelial cells throughout 

 its whole length : in these the nuclei are compact, spindle shaped 

 and are situated near the base of the cells (PI. VIL, Fig. 100). 

 In somewhat advanced larva?, at about the 9 p. c. stage, the 

 walls of the oesophagus contain uncellular glands here and there. 

 In life the movement of cilia on the oesophageal walls is very 

 distinct, even when the animal is at rest, and a constant current 



