Rajjd. — Nerve-Cell Centrosome. 



PLATE 4. 



Fig. 18. Anterior end of the nerve cord of Figure 14, sliowing a mass of newly 



formed cells. (7 da^'s' regeneration.) X 160. 

 Fig. 19. Parasiigittal section through the middle region of one lobe of the brain of 



a normal worm. X 160. 

 Fig. 20. Parasagittal section through the middle region of one lobe of a brain of 



34 days' regeneration. X 1*30. 

 Fig. 21. A dividing cell in tlie prophase and one in the metaphase (one pole cut 



away) from a brain of 34 days' regeneration. X 2000. Iron-ha;ma- 



toxylin. 

 Fig. 22. Metaphase from a brain of 34 days' regeneration. X 2000. Iroa- 



haematoxylin. 

 Fig. 23. Metaphase from the anterior end of a cord after 34 days' regeneration. 



X 2000. Gentian violet. 

 Fig. 24. Metaphase from a brain of 34 days' regeneration. X 2000. Gentian 



violet. 

 Fig. 25. Telophase from a brain of 34 days' regeneration. X 2000. Gentian 



violet. 

 Fig. 26. Telopliase from tlie posterior dorsal region of a brain of 34 days' re- 

 generation. X 2000. Iron-hiemato.xylin. 



