630 E. J. HARVEY GIBSON ON THE 



The cells are narrow and tapering. The nuclei are long, and usually contain 

 two nucleoli and granular protoplasm (PL CXLIX. fig. 12). The cells 

 are slightly swollen in the position of the neuclei. They spring from 

 a more or less homogeneous layer of dense connective tissue, which acts as a 

 basement membrane. The epithelial cells are connected to this layer by fine 

 processes, which give their inner ends a serrated appearance. The connection 

 can, however, be easily made out in their sections under a high power. The 

 cells are not closely arranged, but leave spaces between, filled probably with 

 cement substance, so that a greater degree of contraction and extension is 

 thus attainable in the tentacle. The outer ends of the cells are widened some- 

 what, and become continuous with a homogeneous and relatively thick (in the 

 contracted condition) cuticle, which is highly refractile, stain bright yellow with 

 picric acid, and is therefore probably elastic in its nature. The cuticle on its 

 under aspect is lined by a layer of granular protoplasm formed apparently by 

 the fusion of the ends of the epithelial cells. The epithelial cells become more 

 cubical nearer the base of the tentacle. The subepithelial connective tissue 

 layer is not so apparent at the tip of the tentacles, where the distinctly tapering 

 epithelial cells are seen to be continuous with fibres in the mass of the tentacle. 

 In the thicker part of the tentacle the subepithelial layer may be seen to give 

 off fine processes, similar to those which connect the subepithelial layer to the 

 epithelial cells, to join the feltwork of connective tissue of the body of the 

 tentacle (PL CXLIX. fig. 14). 



At the tip of the tentacle the connective tissue layer immediately subjacent 

 to the epithelial layer is pigmented, the pigment being in the form of minute 

 rounded granules. No pigment is found in the epithelial cells in that position. 



The muscle of the tentacle is disposed in a longitudinal manner, running 

 from the base to the tip (PL CXLIX. fig. 11). The muscle fibres are arranged in 

 loose irregular strands, which may be seen to branch and unite again at intervals. 

 There is a tolerably distinct layer of longitudinal fibres beneath the epithelial 

 cells, especially en the outer aspect of the tentacle, the larger fibres being 

 ventrally placed. There are many transverse fibres, not arranged in any definite 

 bundles ; also a few oblique fibres. There are no circular fibres, nor are they 

 required. The muscle fibres are of the type described under the muscular 

 system. 



Connective tissue, and a reticulum of connective tissue corpuscles, fill up the 

 rest of the body of the tentacle. The connective tissue is of the ordinary type, 

 a dense feltwork of homogeneous and fibrillated fibres against and among which 

 lie many nucleated connective tissue corpuscles. One or more nerve branches 

 are found occupying the centre of the tentacle. Each is made up of a bundle 

 of very fine wavy fibres, amidst which may be seen minute red-stained nuclei. 

 The nerves branch and give off fibrils to the bands of muscle. 



