SPECIAL ANATOMY. 73 



the diameter of the larger ones and nuclear bodies. The globules are 

 more or less polygonal, from mutual pressure, are distinctly granular, 

 and contain a nucleus which is comparatively of enormous size. The 

 latter usually fills one half or two thirds of the cell or globule, is more 

 distinctly and darkly granular, and contains from one to seven small, 

 round, transparent nucleoli. The separate nuclear bodies resemble the 

 nuclei of the ganglion globules, but are much smaller, and contain 

 but a single nucleolus. The nerve-fibres pass through the ganglionary 

 centres, among the globules in every direction ; but none of them ap- 

 pear to originate or terminate in the latter. None of the ganglionary 

 cells are caudated. 



The nerves consist of bundles of tubuli, containing an oleo-albumi- 

 nous matter, which in the fresh nerve is semi-fluid, faintly granular, 

 homogeneous, and translucent, but after the matter is pressed out of 

 the tubuli it separates into two portions, one of which is a tenacious, 

 fluid substance, containing the other in the form of oil-like globules of 

 no determinate size. The wall of the tubuli is amorphous and trans- 

 parent, and has attached to it, and projecting externally, ovai, granular 

 nucleolated nuclei. 



The nerves, especially in those emanating from the supra-oesophageal 

 ganglia, are enveloped in a sheath formed of large, elongated, polygonal, 

 transparent cells, containing in the centre an Oval nucleus surrounded 

 by a mass of coarse granular bodies, which are endowed with a very 

 active molecular movement. 



On the Organs of Especial Sense. 



Touch. The soft, mucous integument is very irritable ; but tactile 

 sensibility is most developed in the tentacula and eye-peduncles, which 

 are two pairs of tubular prolongations of the external integument, from 

 the anterior part of the body or head. The superior pair, or eye-pedun- 

 cles, are several times longer and thicker than the inferior pair. They 

 are conico-cylindroid in shape, with the free extremity or point dilated, 

 or bulbous, in the outer side of which the eyes are placed. The infe- 

 rior pair, or tentacula, are short, conico-cylindroid, and slightly bulbous 

 at the point. 



The integument is thick at the base of the tentacula, but gradually 

 becomes thinner as it approaches the free extremity, where it is deli- 

 cate and transparent. The color is the same on the general investment 

 of the body, except at the free extremity of the tentacula, where, from 



