The Organism and its Protoplasm 145 



ciona prolifera, witli those of Lissodendoryx carolinensis^ 

 and M. prolifera with Stylotella heliophila. In both cases 

 the larger fragments were discarded, and only the cells and 

 small cell masses experimented with. These were thoroughly 

 mixed together in watch glasses by jets of water from a 

 pipette. "The mixture was spread evenl}^ over the bottom 

 of tile watch glass, and looked like a fine sediment." But 

 the cells of each species could be readily distinguished, those 

 of Lissodendoryx being greenish and those of Microciona 

 being briglit red (to speak of these two species). "Fusion 

 began, and the bottom w^as soon covered, no longer with a 

 continuous 'sediment' but with discrete small masses, some 

 red, some green. ... In general red mass fused with red 

 mass, and green mass with green mass. Nevertheless fusion 

 was also observed in some instances betw^een red and green 

 masses. . . . Such fusions, as the further history of the 

 watch glass showed, must have been temporary or the com- 

 bined masses soon died. For as fusion progressed and the 

 masses increased in size, the distinction between red and 

 green tissue became more evident." -^ The outcome was 

 that, young sponges of pure Microciona were developed but 

 none of Lissodendoryx, the development going no further 

 than the early fusion stages. Likewise in the mixture of 

 Microciona and Stylotella there was no fusion between the 

 cells of the two species nor was there a full development of 

 Stylotella sponges alone. 



The point wherein these negative results are somewhat 

 less conclusive than might be wished is that neither in Lis- 

 sodendoryx nor Stylotella were full fledged young sponges 

 produced from the dissociated tissues even when these were 

 treated each species by itself. It may be said that a fusion 

 of two species could not be expected if one of them is in- 

 capable of fusion and development alone. Nor is this ob- 

 jection fully met by the fact that in one of the species at 

 least, Lissodendoryx, the early stages, that is the fusion 



