DEVELOPMENT OF SPONGES FROM TISSUE CELLS OUTSIDE 

 THE BODY OF THE PARENT. 



By H. V. WILSON, 



ProjessoT oj Zoology, University oj North Carolina. 



About five years ago I suggested to the Bureau of Fisheries that an investi- 

 gation to cover the various ways in which sponges reproduce might yield some 

 results of value for scientific sponge culture. I had in mind the high degree of 

 reproductive (technically, regenerative) power possessed by at least certain 

 body cells, as distinguished from germ cells, in sponges. 



This great regenerative power of somatic cells in sponges is displayed, as 

 has long been known, in the formation of asexual masses which under proper 

 conditions develop into new sponges. The regenerative masses of this kind that 

 are best known are the gemmules of fresh-water sponges, but similar gemmules 

 have been discovered by Topsent and others in marine sponges. Observations 

 of my own, dating as far back as 1889," indicated that in some marine sponges 

 such asexual masses not only possess the power to transform into sponges, but 

 in so doing pass through a swimming stage not distinguishable from the ciliated 

 larva which typically develops from an egg. In a case of this kind, as I have 

 pointed out (op. cit., 1891), the nature of the body cell as measured by its poten- 

 tialities is fundamentally like that of a germ cell — it has full regenerative power, 

 including the ability to recapitulate in some measure the ancestral history of 

 the protoplasm. Considerations of this kind led me to doubt whether in all 

 metazoa the protoplasm really did divide sharply into somatic and germinal 

 cells. Rather was the idea encouraged that in the lower metazoa, such as 

 sponges, the cellular elements all retained just so much of the nature of the 

 germ cell (just so much of the specific idioplasm, one might say) as would enable 

 them, under the influence of an appropriate stimulus, to develop either into ova 

 or sperms, or into asexual reproductive masses. Assuming that sponge proto- 

 plasm had this eminently plastic character, I conceived that one might discover 

 ways in which to call into unusual activity the reproductive or regenerative 

 power, and so, as it were, to invent new methods of growing sponges. 



" Wilson, H. v.: Notes on the development of some sponges, Journal of Morphology, 1891; Obser- 

 vations on the gemmule and egg development of marine sponges, ibid., 1894. 



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