252 H. V. Wilson 



them a new name, that of sorites.^ It is clear then that in many- 

 sponges reproductive bodies are formed by the association of 

 unspeciaHzed amoeboid cells. But there is nothing in this fact 

 which precludes the possibility that the groups of amoebocytes 

 are in part recruited from transformed collar cells and other tissue 

 cells, such as pinacocytes (flat cells of canal walls), that have 

 undergone regressive differentiation into an unspecialized amoeboid 

 condition. 



Cells analogous to the amoebocytes of sponges are found else- 

 where in the metazoa, e. *g., in the ascidians.^ It would be inter- 

 esting to know what capacity, if any, for development they have, 

 when freed from the parent (bud) and collected together in sea- 

 water. 



II 



I shall here briefly record some experiments which gave only 

 negative results but which under circumstances admitting of a 

 wider choice of species, ought to yield returns of value. These 

 experiments were based on the assumption that if the dissociated 

 cells of a species will recombine to form a regenerative mass and 

 eventually a new sponge, the dissociated cells of two different 

 species may be made to combine and thus form a composite mass 

 bearing potentially the two sets of species-characteristics. It is 

 clear that such an organism would be analogous to one produced 

 by an association of the blastomeres of the two species. Pending 

 the successful carrying out of this experiment, it would be idle to 

 discuss further the nature of the hypothetical dual organism. 



In my own experiments three sponges were used: Microciona, 

 Lissodendoryx and Stylotella. The three are all monactinellids, 

 but Microciona is the only one in which the skeleton includes any 

 considerable amount of horny substance. Dissociated cells of 

 Microciona and Lissodendoryx were mixed, and again dissociated 

 cells of Microciona were mixed with those of Stylotella. In each 

 case the experiment was performed at two different times, and a 

 considerable number of admixtures, in watch glasses and on 



s Wissensch. Ergebn. d. Deutsch. Tiefsee-Exp. 1898-99. Hexactinellida, pp. 213-15. Jena, 1904. 

 ' Comp. Hjort's and Lefevre's papers on budding in ascidians. 



