14 2(S-S.444) THE MONONCHS 



its length ; it may diminish a trifle in the vicinity of the nerve-ring, while 

 in the posterior half it usually expands a trifle, so that finally it is one- 

 half to two-thirds as wide as the corresponding portion of the body. The 

 refractive lining of the oesophagus is strongly developed, and is of such a 

 character that its longitudinal optical section often occupies as much as 

 one-third of the diameter of the whole organ, sometimes one-half, excep- 

 tionally even more. The radial musculature of the oesophagus is strongly 

 developed, and usually appears coarser posteriorly than anteriorly. 



(Esophageal Glands. In some species, very likely in all, among the 

 interstices of the cesophageal muscles there exist glandular tissues, which 

 empty their secretion into the lumen of the oesophagus through minute 

 pores in the lining, situated from place to place throughout a considerable 

 portion of the length of the organ. Some of these glands appear to 

 empty into the pharynx, but the best developed ones occur in the dorsal 

 section of the oesophagus near the middle. 



De Man and Micoletzky mention structures in the wall of the pharynx 

 of Mononchus, about the nature of which they seem doubtful, but sug- 

 gest the possibility that they are pores. My observations lead me to the 

 conclusion that some of the more minute so-called "teeth" or denticles 

 of authors, at the bottom of the pharynx, and even some of those higher 

 up, are in reality elevated pores connected with glandular structures in 

 the anterior part of the oesophagus. These pores appear to me to be the 

 homologues of the pores which I have demonstrated undoubtedly to 

 exist farther back in the oesophagus, and to be the outlets of glands 

 located in the interstices of the radial muscles. See fig. 9. 



It is easy to believe that the cesophageal glands are salivary glands, and 

 that they serve the mononchs in gorging down food in somewhat the 

 same way as do the glands of serpents. This surmise 

 is based upon the structure and position of the 

 organs rather than upon definite and extensive physio- 

 logical experiment; intra vitam stains, however, have 

 shown that the secretions of these glands are alkaline, 

 evidence supporting the surmise. 



Intestine 



Cardia. There is usually a flattish cardia consist- 

 ing of 20 to 50 small characteristic cells that stain 

 cross' section of in- rather strongly with acid carmine, and manifestly dis- 

 Sdatiwto ?ho4 coi- charge a distinct function. The intestine, which is 

 thTiininK tr of tU th e e in- invariably separated from the oesophagus by a deep and 

 prominent constriction, becomes at once about three- 

 fourths as wide as the body, and is usually made up of cells of such a 

 size that about 8 to 20 are required to build a circumference. These cells 

 contain numerous granules of somewhat variable size, often so arranged 



