* 9 ° 7 \ 
Some Phenomena in Sponges 
169 
II 
I shall here briefly record some experiments which gave 
only negative results but which under circumstances admit- 
ting 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 disso- 
ciated cells of two different species may be made to com- 
bine 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 associa- 
tion of the blastomeres of the two species. Pending the suc- 
cessful 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: Micro- 
ciona, Lissodendoryx and Stylotella. The three are all mon- 
actinellids but Microciona is the only one in which the- skele- 
ton includes any considerable amount of horny substance, 
j 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 per- 
formed at two different times, and a considerable number of 
admixtures, in watch glasses and on cover glasses, was made. 
The preparations were examined at short intervals with the 
microscope. The cells of these three species are colored very 
differently, and are therefore easily distinguished, at least as 
soon as fusion sets in and little masses of cells begin to be 
formed. In all the experiments the cells and cell-masses of a 
species cdmbined and not the cells of different species. Thus 
in the admixture of Microciona and Lissodendoryx, Microci- 
ona regenerative masses and Lissodendoryx regenerative 
masses were produced. Similarly when Microciona and Styl- 
otella cells were mixed, the resultant masses were pure, some 
Microciona, some Stylotella. The Microciona masses in these 
^experiments were hardy. They continued to develop and in 
some preparations metamorphosed. The cell masses of the 
lother two species while they reached a considerable size were 
