rand: nervous system of lumbricid^. 115 



cles. The structure in Figure 9 is very similar to that in Figure 3. 

 The central body may consist of two granules, but they could not be 

 clearly separated. 



Figure 4 (Plate 1) represents a condition frequently met with. There 

 is, in the cell drawn, a condensation of finely granular cytoplasm ex- 

 tending halfway from the centre to the periphery of the cell. Tliis is 

 probably in no way comparable to such a sphere as is shown in Figures 3 

 and 9. It is not sharply outlined, and it lacks the bounding layer of 

 granules. The body at the centre of this finely granular region is sur- 

 rounded by a clear space ; and radiations, lacking, however, any con- 

 spicuous gi'anules, extend toward the cell periphery. Cells of this 

 character may best be considered as belonging to the first type (Figure 1), 

 as far as the structure of the radiating system is concerned. 



2. The Nerve Cells of Nereis. 



In the ventral ganglia of Nereis are certain large cells situated near 

 the median plane and having their nuclei in their dorsal or process 

 ends. The nuclei are often flattened or invaginated on the side toward 

 the cell centre. In one very large cell with an invaginated nucleus an 

 intensely stained granule was seen lying in the concavity of the nucleus, 

 and around the granule were several fine radiations. The cj^toplasm 

 was completely decolorized, the granule mentioned being the only stained 

 object in it. This appeared to be a good case of the " centrosome." 

 Nereis was not studied sufficiently to determine whether such structures 

 are commonly present. 



3. Outline op the Process of Regeneration of the Brain 



AND Anterior Ganglia. 



The regeneration of the anterior ends of the worms (Allolobophora) 

 took place substantially in the manner described by Hescheler ('98). I 

 have made no preparations at periods of regeneration earlier than seven 

 days. 



Figure 14 (Plate 3) represents a parasagittal section of the anterior 

 end of a worm after seven days' regeneration. The limit of the 

 old tissues is easily distinguishable in all such early stages, and, in 

 fact, there is no difficulty, up to a comparatively late period, in distin- 

 guishing old tissues from those that are being regenerated. In Figure 14 

 the old epidermis ends at points designated by the asterisks. The new 



VOL. XXXVII. — NO. 3 3 



