74 On the Nervous System of Actinia. 



plasm, granules, and granular cells, which merge gradually into the 

 close layers of granular cells under the Kotteken bodies, and they 

 transgress here and there on those layers. 



The fusiform cells are numerous (PI. LXIX., Figs. 18-24), and 

 may be divided into two kinds: — (a) Those with irregular shapes 

 and short terminal processes, which are prolongations of the cell- 

 wall and are rounded off. These cells contain either highly refrac- 

 tile nuclei, or several nuclei with granular nucleoli. The fusiform 

 shape is not invariable, and in Plate LXIX., Fig. 20, a large cell 

 twice the diameter of a Ptotteken body is seen amidst the granular 

 plasm. It has a tail-shaped prolongation and some highly refrac- 

 tile nuclei. 



/S. Those which are rounded in outline, and whose projections 

 are long and continuous with those of others. The outlines of these 

 cells are soft, and without definite and sharp margins, and the 

 colour is a very pale blue-grey. They contain one or more very 

 distinct nuclei. Our type, illustrated in Plate LXIX., Fig. 21, has 

 its cells rather wider than a Eotteken body, and they are connected 

 by a process with sharply-defined wells — the cell, with many nuclei, 

 having a long caudal fibril of a pale grey colour and rather sharp 

 marginal lines which had suffered disruption. 



A second type has large spherical or elliptical cells, which do 

 not have processes passing out in opposite directions, but they are 

 restricted to one part. Usually the cells have only one process, 

 but sometimes two exist close together (Fig. 22). 



These cells are granular within and have very indistinct nuclei ; 

 the cell-wall is extremely delicate, and the whole is of a pale grey 

 colour. The fibrils of these cells are particularly connected with 

 the plexiform tissue. In Plate LXIX., Fig. 22, there is a cell with 

 two fibrils — one is short, for it dips down and is foreshortened, 

 and the other is very long ; it bifurcates, and one end joins a 

 rounded mass of the plexus, and the other the rugged fibrillar 

 part. 



In Plate LXIX., Fig. 24, a cell with one fibril is shown. The 

 fibril swells slightly, and then passes down to join a transverse 

 fibre belonging to the plexus. 



The plexiform tissue is probably continuous around the Actinia 

 beneath the chromatophores, for it is found between the circular 

 band of muscular fibres and every chromatophore. It consists of 

 an irregular main structure and of lateral prolongations, which 

 either anastomose with the fibrils from the fusiform and more 

 spherical cells, or are directly continuous with the cells (Fig. 23). 



The main structure resembles, in its indistinctness of outline 

 and its pale grey colour and indefinite marginal arrangement, the 

 fibre of the sympathetic of mammals, but it is less coherent and 

 smaller. The usual appearance (PL LXIX., Fig. 23) is that of a 



