PLATE 28 



Figs. 9-12. Series of longitudinal sections through the anterior end of Balan- 

 tidium ooli (Malmsten). X 1000. These sections are oblique, being more nearly 

 frontal than sagittal, however. The section shown in figure 9 is tangential to the 

 margin of the peristome some distance to the right of the most dorsal point of the 

 latter (see fig. J in text). The remainder progress toward the left ventral lip. 

 The oral plug fibers, the radial fibers, and the adoral ciliary rootlets are shown 

 clearly in these sections. 



Fig. 13. A sagittal section through Balantidium suis (sp. nov.). X 1000. 

 The specific characters, viz., elongate body and macronucleus, and oblique plane 

 delimiting apical cone of ectoplasm, are shown in this section. The cytopyge is 

 distinct and open to the exterior. A paramylum body of considerable size is 

 present in the endoplasm. 



Fig. 14. An oblique longitudinal section through Balantidium coli (Malmsten) 

 showing the protrusion of the oral plug. X 750. 



[300] 



