HAMAKER. — Nervous Syst. Nereis, 
PLATE 2. 
Fig. 9. Transverse section through the posterior end of the brain. 
Fig. 10. Pigment (?) from the posterior part of the brain. 
Figs. 11 and 12. Nerve cells of the fourth and third classes of the brain respectively. 
Fig. 18. A group of four ganglionic cells of a segmental ganglion, in frontal 
section, to show centrosomes. 
Fig. 14. A, ordinary ganglionic cell. B, one of the large cells of set B (compare 
Fig. 27). The cytoplasm is not granular and takes little stain, ex- 
cepting the large irregular granules around the centrosomes, 
Fig. 15. Brain nerve cell of the second class. 
Figs. 16 and 17. Brain nerve cells of the sixth class. 
Fig. 18. Transverse section through the posterior end of a segmental ganglion 
from the region of the fifteenth segment. It shows the connection 
between the neurilemma and the tunica intima of the ventral blood- 
vessel; also the position of the ventral nerve cord relative to the hypo- 
dermis and the circular muscles. 
Fig. 19. Brain nerve cell of the fifth class. 
