120 ILLINOIS BIOLOGICAL MONOGRAPHS [120 



DESCRIPTION OF PLATE 



Fig. 149. — Cercaria gracillima; genital cell masses. X 270. 



Fig. 150. — Cercaria gracillima; nervous system. X 540. 



Fig. 151. — Cercaria gracillima; central nervous system in a very young germ-ball. X 540. 



Fig. 152. — Cercaria gracillima; transverse section thru esophagus glands. X 540. 



Fig. 153. — Cercaria gracillima; transverse section thru region slightly posterior to that shown 



in Fig. 152. X 540. 

 Fig. 154. — Cercaria gracillima; transverse section thru salivary glands. X 540. 

 Fig. 155. — Cercaria tuberistoma; ventral view. X 170. 

 Fig. 156 A-F. — Cercaria tuberistoma; stages in development. X 75. 

 Figs. 157, 158. — Cercaria tuberistoma; sporocysts. X 54. 

 Fig. 159. — Cercaria biflexa; section thru liver tissue of Physa gyrina Say, showing infection; 



a, disintegrating cectun; b, broken down connective tissue; c, section of worm. X 170. 

 Fig. 160. — Cercaria micropharynx; section thru liver tissue of Lymnaea proxima Lea, infected 



with the worm; a, fatty bodies in degenerating cecum; b, vacuoles; c, sloughing tissue; 



d, karyolysis; e, section of worm. X 170. 

 Fig. 161. — Cercaria gracillima; section thru Uver tissue of Physa gyrina Say infected with 



the worm; a, cytolysis; b, fatty globules; c, karyolysis; d, vacuoles; e, fibromata;/, sand 



inclusions; g, section of worm. X 240. 



