DEVELOPMENT OF SPONGES FROM DISSOCIATED TISSUE CELLS. 



By H. V. WILSON, 

 Professor of Zoology, University of Korlh Carolina. 



This investigation was carried on at the Beaufort Laboratory of the Bureau of Fish- 

 eries during the summers of 1907 and 1908. An outline without illustrations of the 

 results has been published in the Journal of Experimental Zoology (On Some Phenomena 

 of Coalescence and Regeneration in Sponges, vol. v, no. 2). In papers read before the 

 Fourth International Fisheries Congress (Washington, September, 1908) and t,he Amer- 

 ican Society of Zoologists (Baltimore, December, 1908), I made brief mention of the 

 results and in connection therewith exhibited specimens and photographs. It now 

 seems desirable to publish the facts, with illustrations, in sufficient detail for the account 

 to be useful as a guide in future investigations. 



MICROCIONA PROLIFERA. 



This species, known as the red oyster sponge, is common in Beaufort Harbor and is 

 the form I have chiefly used in my experiments. 



DESCRIPTION t)F SPECIES. 



Diagnosis. — Incrusting at first, but later forming lobes, and eventually becoming a complex 

 branched body. Color, red. Skeleton in incrusting type a basal homy plate with short upright 

 plumose columns. Skeleton of branched sponge a reticulum of spiculofiber. Characteristic mega- 

 sclercsare: (i) Smooth style, 400-160/1 long, 8-1 6/i thick; (2) small spinose style, 80/1 by 6/i. Microscleres 

 are isochelEe, 12-16/1 long, and toxas 16-40/1 long, both, but especially the latter, scantily present. 



Verrill and Smith have pointed out that the habitus viiries greatly, and have indicated the chief 

 types. The sponge may form thin incrustations, especially on oyster shells and on wharf piles. Such 

 incrustations may be entirely without lobes, or may bear a few projecting lobes as is the case with the 

 specimens shown in figure 2, plate i. Older specimens are not infrequently found in which the forma- 

 tion of the lobes has gone on with accompanying branching and anastomosis, such growth eventually 

 producing an intricately branched sponge body (fig. i, pi. i). Specimens of this type may reach a 

 height of 150 mm. 



Structure of incrusting type. — In the incrusting specimens the skeleton consists of a homy basal 

 plate bearing closely set vertical homy columns from which the larger spicules (megascleres) project. 

 A section through such a sponge is shown in figure 5, plate i. From near the apex of each homy column 



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