Dr Grant on the Structure and Nature qf'Flustrae. 115 



fleshy tubular process is sent off, which terminates in a large oblong fleshy 

 sac, generally filled with some opaque matter. As this process is nearly as 

 thick as the part of the body from which it comes, the polypus appears bifur- 

 cated at its shut extremity. At the pointy of the bifurcation, the polypus ap- 

 pears to be somehow connected with the centre of the posterior wall of the 

 cell ; and every other part of the polypus, excepting this, moves freely in the 

 cavity of the cell. The last remains of the dead polypi are found at this point 

 of the cell, with vessels radiating from them. From the point of the bifur- 

 cation to the entrance of the round sac, we perceive a kind of circulation con- 

 tinually going on within the fleshy tube ; it consists in the constant revolu- 

 tion of the particles of some fluid, probably caused by cilise disposed on the 

 internal surface of the canal. The tapering or posterior part of the body of 

 the polypus sometimes exhibits small portions of digested matter passing to 

 and fro within it. The round shut sac containing the opaque yellow matter 

 moves often, and quite freely, within the cell ; and it appears to belong rather 

 to the digestion than to the generation of this animal, as it communicates 

 directly with the digestive canal of the polypus, and it will be seen that the 

 polypus of this animal has as little to do with the formation and growth of 

 the ova, as it has in other zoophytes. 



In place of finding the polypi alive only near the margins of the branches, 

 as Lcefling, Lamark, and others have maintained, we find them almost equally 

 abundant and healthy in every part, from the base to the apex, and from the 

 centre to the margins of the branches. The cells along the sides of the 

 branches , are generally imperfectly formed, and contain no polypi ; their 

 outer calcareous margin is for the most part wanting. The last two or three 

 rows of cells, at the extremities of the branches, are thin, soft, gelatinous, 

 and transparent ; and contain young polypi so imperfectly formed, that it is 

 quite obvious that the extreme row could not have been generated by the 

 polypi of the second row, after their arriving at maturity. The extreme 

 margin of the branches always presents a smooth and even outline from the 

 equal growth of every point of the axis, and never exhibits the notched or 

 serrated line, which would be produced by the unequal developement of a 

 terminal row of gemmules. The cells newly formed in the soft gelatinous 

 terminations of the branches, have the same size and form as the oldest 

 cells, so that we find at the extremities of the branches a row of imperfect 

 cells in every stage of their formation. Some of these imperfect cells do 

 not yet exhibit the rudiments of a polypus ; some a little further ad- 

 vanced exhibit an opaque spot at the base, from which tentacula at length 

 shoot cut like buds ; other cells, more nearly completed, present the 

 young polypus inclosed in a long shut sac, tapering upwards to the point 

 where the aperture of the cell is afterwards formed ; and others, which 

 only want their upper arched wall, contain perfectly formed polypi, ca- 

 pable of projecting their tentacula and head through the opening of the cell ; 

 their parts are very transparent and colourless, and their globular appendix 

 appears empty. The sides of the cells form continuous, ramified, and waved 

 lines, from the base to the apex of the branches ; and the growth of the axis 

 in this, as in every other zoophyte, precedes the growth and formation of the 

 polypi. The ax%s of this zoophyte consists in the parietes of the cells, and it 



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