PLATE 3. 



Figs. 12, 14, 15, IS, 19, 20. Prepnrations made by use of chloroform, methylen 

 blue, and Bethe's ammonium molybdate for invertebrates. 



Figs. 13, 16, 17. Prepared by use of sea-water and alcohol, sublirr.ate-acetic, 

 Kleinen berg's haematoxylin. 



Fig. 12. Papilla from cross section of proboscis, showing connective-tissue fibres 

 passing into the papilla; deep coloration of terminal fibrils; the nerve fibres 

 bending in opposite directions where they enter the nerve plexus. X 080. 



Fig. 13. Papilla from cross section of proboscis, showing corrugations of 

 posterior face of papilla, and the outline of one of the basal nuclei. X 460. 



Fig. 14. Papilla from sagittal section of proboscis; the two sensory (axial) 

 cells, their peripheral terminations, and their proximal nerve-fibre prolonga- 

 tions stained blue. 



T lie nucleus of one of the sensory cells more deeply stained than the cell body. 

 Cuticula distended and detached from substance of the papdla by treatment. 

 X 710. 



Fig. 15. Papilla from cross section of proboscis, showing deeply stained axial 

 body, from winch a single peripheral, deeply stained process extends to the apex 

 of papilla, where it terminates in a specialized and stained area ; the contents of 

 the papilla in great part fibrous. X 1020. 



Fig. 1(5. Somewhat oblique cross sections of two papillae from a cross section of 

 the proboscis. In one papilla are two basal nuclei and a part of one of the 

 axial nuclei ; in the other the three axial nuclei cut crosswise. X 070. 



Fig. 17. Cross sections of two papillae from a cross section of proboscis. In one 

 are seen two axial nuclei, each surrounded with a clear area; in the other a 

 basal nucleus and portions of two axial ( ' ) nuclei. X 070. 



Fig. 18. Papilla from cross section of proboscis. The two sensory cells are 

 stained throughout ; their distal prolongations have a more or less spiral course 

 and terminate in a cluster of discs at the apex of the papilla. Vacuoles large. 

 X 715. 



'Fig. 19. Papilla from cross section of proboscis, showing that where the cen- 

 tripetal fibres from two sensory cells meet the nerve plexus, one bends to the 

 right, the other to the left. X 725. 



Fig. 20. Papilla from cross section of proboscis, showing the basal position of 

 the sensory cell body (?) ; the basal end of each sensory cell is prolonged into a 

 slender nerve fibre. X G82.5. 



