2^2 OTT. [Vol. VII. 



become gradually smaller toward the point where occurs the sud- 

 den change in the form of the epithelial cells. At this point 

 occurs the transition in the relations of the muscle fibres to the 

 epithelial cells. Thus these changes in both the epithelial cells 

 and the muscular wall coming at the same point mark off the 

 pharynx from the cone-shaped depression. 



Surrounding the pharynx and in contact with the muscular 

 wall is a large number of pear-shaped cells (Fig. 6, S). When a 

 living worm is treated with methylin blue these cells alone are 

 stained, and it may then be seen that they are distributed uni- 

 formly over the whole pharyngeal region. In longitudinal sec- 

 tions also they may be seen to be distributed over the whole 

 length of the pharynx. These cells are connected with the wall 

 of the pharynx by their smaller ends. There is a great variation 

 in their size. Some are no larger than the ciliated cells of the 

 pharyngeal wall, while others are so large that they reach nearly 

 to the body wall of the worm. The largest of these cells are 

 20 II long and 4 //. wide, while the smallest are 3 jx long and 

 I /x wide. Many of the small cells represented in Fig. 6 are 

 but parts of the larger cells which have been cut in the sec- 

 tioning. 



Many of the largest cells are seen to connect with the pharynx 

 by long stalks which, according to Graff (82, p. 259), run through 

 the pharyngeal wall and open into the lumen. I was not able to 

 trace them through the wall. In a longitudinal section (Fig. 7) 

 I could trace a stalk between two of the outer circular fibres, but 

 could not trace it farther. 



These pharyngeal cells lie free in the body cavity with no 

 other attachment than that of their narrow ends at the wall of 

 the pharynx. They are supported by the parenchyme and the 

 numerous muscle fibres which run between them. 



They are coarsely granular and have very large ovoid nuclei 

 (Fig. 6, TV.) in their large ends. Some of the largest nuclei 

 are 3 /i long and 2 /a wide. They take the hsematoxylin stain 

 freely and become very dark in nearly all cases. 



The muscular wall of the pharynx is connected with the mus- 

 cular wall of the integument by numerous muscle cells. These 

 muscle cells may be divided into two sets. The first set which 

 I shall call radial muscle cells radiate from the pharynx to 

 the integument (Fig. 8, R.M.). 



