THE VISCERAL MASS IN ANTEDON ROSACEUS. 305 



above the surface of the rosette plate to a height of three-fifths of a 

 millimetre. The strands of connective tissue which support it appear 

 to be continuous with the organic basis of the first radials. 



In sections of the isolated visceral mass we fiud that the aboi'al sur- 

 face is covered by a thin layer of connective tissue, which has on the 

 outside a very distinct outline, caused by an extremely thin, deeply 

 staining layer which is possibly epithelial. In sections of an uninjured 

 Antedon this layer is seen to rest on the layer of tissue already de- 

 scribed as forming the floor of the visceral basin, and is connected 

 with it by very delicate bands of connective tissue which run across 

 from the one to the other. 



Thus, in the process of evisceration the separation of the visceral 

 mass takes place between two layers of connective tissue — the one 

 lining the surface of the visceral basin and the other covering the 

 aboral surface of the visceral mass. 



The Kegeneration of the lost Visceral Mass. — Unfortunately 

 the series of specimens at my disposal is still very incomplete and it 

 is as yet impossible to give a complete account of this process. For 

 the sake of convenience I ' shall divide the description into several 

 parts, according to the length of time for which the specimens treated 

 of have been regenerating ; but it must not be thought that all speci- 

 mens which have been regenerating for the same length of time have 

 arrived at the same stage in the process ; this is by no means the case, 

 and I find that different specimens of the same date present consider- 

 able variations. The regenerated specimens of forty-three hours are 

 from the Firth of Clyde, those of later dates from Naples. 



Forty-three hours. — The connective tissue lining the floor of the 

 visceral basin has begun to thicken. As a result of this the two circlets 

 of muscles already described are much less distinct than in a freshly- 

 eviscerated specimen, although still plainly visible. The thickening 

 is more marked around the edges of the injured area than in the 

 centre, so that the inner circle of muscles is much more distinctly 

 visible than the outer one ; in one specimen of this date the outer 

 circle of muscles is nearly hidden by the ingrowing mass of connective 

 tissue. The line of tear, along which the visceral mass has been sepa- 

 rated from the calyx, no longer appears sharp and distinct. 



Ttoo days. — The new growth of connective tissue, which had com- 

 menced at forty- three hours, has proceeded further. The circlets of 

 V 



