708 TROCEEDINGS OF THE ACADEMY OF [DeC. , 



The oesophagus extends backward from the mouth a distance of 

 about 9-12 ram., according to the size of the worm. The wall 

 of the oesophagus, figs. 31, 33, consists of an epithelium oE ciliated 

 supporting cells, S.C., and gland cells, GL^, about .023 mm. in 

 height, very similar to that of the epidermis (cf. figs. 2 and 31). 

 The supporting cells are like those of the epidermis, only more 

 slender. The gland cells are flask-shaped, with finely granular 

 contents that stain a bright pink, htematoxylin-eosin staiu. Blue- 

 staining gland cells are entirely absent. Both supporting and 

 gland cells rest on a delicate basement membrane, B.M., and 

 some interstitial connective tissue cells are found between the 

 bases of the epithelial cells. 



At the extreme posterior end of the oesophagus some of the epi- 

 thelial cells become much higher, but otherwise their structure is 

 the same. 



The subepithelial gland cells, that have been described above as 

 giving the greenish color in life to the circular "lip" of the 

 mouth, are present in great numbers immediately around the mouth, 

 and less abundantly throughout the greater part of the oesophagus. 

 A group of these cells, w., is shown in fig. 31, from the anterior 

 part of the oesophagus. The gland cells are large, the cell body- 

 containing a secretion that is probably fluid in life, but appears 

 finely granular in the fixed preparations and stains rose red, 

 hsematoxylin-eosin stain. Some cells seem to have but one nucleus, 

 others more than one, but the latter case may be due to the crowd- 

 ing together of the cells or to the presence of the adjacent connec- 

 tive tissue nuclei, so that this point has not been definitely settled. 

 The ducts, dt, are long and slender, and open into the oesophagus 

 between the epithelial cells. Farther back in the oesophagus these 

 subepithelial gland cells entirely disappear. 



The inner surface of the oesophagus is usually thrown into 

 numerous high papillre, especially the ventral surface (see fig. 33). 

 The papillse are formed chiefly of hmgitudinal muscle fibres, but 

 contain also connective tissue cells and the subepithelial gland 

 cells, when they are present. The papilla) come to an end together 

 with the oesophagus (cf. the dorsal and ventral surfaces of fig. 33). 



A few isolated strands of circularly running muscle fibres, fig. 

 33, M.S., are frequently found beneath the papilla), partly encir- 

 cling the oesophagus, but no continuous " oesophageal " muscle 



