78 On the Nervous Sijstem of Actinia. 



I have not found any isolated fusiform cells amongst the tissues 

 of the base ; but under the endothelium, and also between the layers 

 of muscular fibres, there are structures which I feel disposed to 

 believe must belong to the nervous system. 1. They are in the 

 position of nerves. 2. Their structure is not that of muscle or fibre. 

 3. Their structure resembles, in some instances, the plexiform 

 tissues beneath the chromatophores. 



The nervous structures are found to present three characteristic 

 shapes : — 



1. A thin layer of muscular fibrils of the small and separate 

 (see 2 above) kind, with well-defined dark nuclei in them, was 

 examined. The whole was very transparent and well defined under 

 the -jJg-inch objective. 



Underlying this layer, and extending on either side beyond it, 

 so as to appear in one of the meshes between groups of these fibrils, 

 was a ramified pale grey tissue, which was less pervious to light 

 than the muscular fibrils (PI. LXX., Fig. 25). Swollen in one part 

 and faintly granular throughout, it had its margins very faintly 

 visible. It was flat, and had a definite resemblance to the widest 

 portion of the plexus already mentioned. 



2. A large section of muscular tissue was examined. It consisted 

 of one layer of large muscular fibres (see 3 above) in close lateral 

 contact. Eunning obhquely over the layer was an irregular but 

 continuous cord ramifying here and there, the branches breaking up 

 into fibrils. In one part the cord was swollen (PI. LXX., Figs. 26 

 and 27). A second ramification passed from the opposite end of 

 the field of the microscope and broke up into ultimate fibrils, and 

 in this structure there was a fusiform ceU. 



Careful manipulation separated a portion of the upper cord 

 from the muscular fibres, but a part of it evidently dropped down 

 amongst them. 



3. A layer of muscular fibres of the same kind as those just 

 mentioned was examined. It was marked, as usual, with the lateral 

 dark lines and pale elongated nuclei. 



Three long and irregular fibres passed more or less obliquely 

 over the muscular tissue (PI. LXX., Figs. 28-30). They had 

 distinct lateral or marginal lines, were swollen out in several places, 

 and their texture was faintly granular. 



I believe that these fibres were continuous with the fine 

 ramifications of the plexiform arrangement just described. 



4. Above the muscular layers, and under the folds of the 

 endothehum, I found an inosculating series of ramifications arising 

 from a common cord. It was situated upon the layer of muscular 

 tissue, with small and separate long fibrils. 



The structure was faintly granular, pale grey in colour, with 

 faint outlines, and was swollen in some places : it covered a con- 



