BY VERA A. IRWIN-SMITH. 



793 



is one cell thick (Figs. 34, .35, <f^.). The cells are thin-walled, and 

 roughly rectangular in cross-section, measuring about 0-014 x 

 007 mm. The protoplasmic contents are clear; and a large, 

 round nucleus {nuc.) is situated about the middle of each cell. 

 In the mid-region of the body, in the female, the intestine is 

 constricted to a narrow tube pressed up against the dorsal wall 

 by the genital organs. Below the posterior ovary, it widens so 

 as nearly to fill the C(eIome. The cells of the wall are here very 

 large, and the cell walls, forming the lining of the passage, are 



iff.JZ 



re. 



rd 



Fig. 39. 



Figs. 86-39. —Gh. hasweUi. 

 Series of tr. sees, through posterior region. Like most of the transverse 



sections, thej' have become distorted in shape during em))edding; 



( X 950). 

 Fig.36. — Section through constriction between intestine and rectum. Fig. 



37, through rectum. Fig. 38, through anal aperture. Fig. 39, 



through tail. 



slightly thickened. The cells vary in shape, and nroject into 



the intestinal cavity, leaving only a narrow passage. The tube 



is constricted again in the region of the ventral sette (Fig. 27, in/.). 



About the level of the last of the ventral setae, the intestine 



57 



