DEVELOPMENT OF SPONGES FROM TISSUE CELLS. 1271 



a paper presented to the National Fishery Congress of 1898° I briefly discussed 

 the possibiUty of improving sponge races, suggesting as means thereto the breed- 

 ing of sponges from the egg with accompanying selection, and also the practice 

 of grafting. Now if the cells of two closely allied races were mixed together it 

 is on the whole probable that a composite Plasmodium would result which would 

 develop the characteristics of both races. Such a form would be something 

 comparable to a hybrid. I have in fact carried on experiments of this character. * 

 The results of my experiments were negative — the cells of each species coalesced, 

 but there was no permanent union between the cells or cell masses of the different 

 species. It should be said, however, that the species used were so unlike that 

 there was at the outset but little chance of coalescence. In a more favorable 

 locality, where a great variety of horny sponges exist, such experiments hold 

 forth some promise. 



Note. — In connection with the foregoing paper there was an exhibit of microphotographs illustrat- 

 ing some of the more important stages in the development of sponges from cells forcibly removed from 

 the parent body. 



o Wilson, H. V. : On the feasibility of raising sponges from the egg. Proceedings of the National 

 Fishery Congress, 1898, in U. S. Fish Commission Bulletin, vol. xvii, 1897. 

 b Journal of Experimental Zoology, loc. cit. 



