THE MINOR OR CEPHALIC SOLE 



415 



pairs or groups ; and each of these two glands proves to have three nuclei. 

 (See Fig. 2.) The cells of each gland, as well as their spheroidal 

 nuclei, increase in size from front to back, the anterior, i.e., distal, 

 cell having less than one-eighth the volume of the posterior; the 

 nucleus in the small anterior cell is also less conspicuous. This group 

 (pair) of glands is more or less clavate in form and is nearly as long as 

 the corresponding body diameter. Posteriorly, each gland diminishes 

 suddenly in diameter to form a duct about half as wide as one of the 

 adjacent annules of the cuticle. Near the gland the wall of the duct 

 contains somewhat elongated nuclei of considerably smaller size than 

 the nuclei of the glands. The duct also lacks the 

 granular character of the glandular cells themselves. 

 The two ducts, at first ventral, diverge backward 

 to the two foremost adhesion tubes, and are one to 

 two times as long as the glands. Near where a duct 

 enters the somewhat swollen base of an adhesion 

 tube, there is a small duplex enlargement or ampulla. 

 In the specimens under examination, only in the very 

 basal portion of the adhesion tube is there any 

 indication of the staining action of the acid carmine. 



The numerous glands composing this ventral 

 series are so closely packed together that, as a rule, 

 it is difficult to distinguish the exact number of 

 groups, but it is evident that throughout the series 

 the glands are arranged in groups side by side, 

 apparently mostly in pairs or quartets, the number 

 of glands being commensurate with the number of 

 adhesion tubes. On occasions when the entire 

 group of glands is slightly separated from the body 

 wall, and therefore from the bases of the adhesion 

 tubes, the ducts leading to the tubes are distinctly 

 visible, and have the appearance, when viewed 

 laterally, of a rather complicated plexus. 



The minor, or cephalic, sole. The dozen or so 

 adhesion tubes and glands of the cephalic sole have 

 the same general plan as the sublateral and sub- 

 ventral ones of the posterior sole just described. 

 The glands connected with the cephalic tubes 

 (gl. pint) are located mainly dorsad in the anterior two-fifths of the 

 neck between the oesophagus and the body-wall; there are two dorsally 



mi!, 



Fig. 2. Anterior 

 ambulatory seta of 

 D. cephalatumvrith 

 its 3-celled gland, 

 its 3-celled mate 

 concealed, though 

 part of its duct 

 shows, del snst.; 

 som, body wall; cl 

 msc, somatic mus- 

 cle; an cut, cuticu- 

 lar annules; mur 

 ext and rwwr int, 

 outer and inner 

 walls of ambula- 

 tory tube; os tb, 

 secretory pore. 



